task_url
stringlengths 30
116
| task_name
stringlengths 2
86
| task_description
stringlengths 0
14.4k
| language_url
stringlengths 2
53
| language_name
stringlengths 1
52
| code
stringlengths 0
61.9k
|
|---|---|---|---|---|---|
http://rosettacode.org/wiki/Echo_server | Echo server | Create a network service that sits on TCP port 12321, which accepts connections on that port, and which echoes complete lines (using a carriage-return/line-feed sequence as line separator) back to clients. No error handling is required. For the purposes of testing, it is only necessary to support connections from localhost (127.0.0.1 or perhaps ::1). Logging of connection information to standard output is recommended.
The implementation must be able to handle simultaneous connections from multiple clients. A multi-threaded or multi-process solution may be used. Each connection must be able to echo more than a single line.
The implementation must not stop responding to other clients if one client sends a partial line or stops reading responses.
| #Common_Lisp | Common Lisp | (ql:quickload (list :usocket))
(defpackage :echo (:use :cl :usocket))
(in-package :echo)
(defun read-all (stream)
(loop for char = (read-char-no-hang stream nil :eof)
until (or (null char) (eql char :eof)) collect char into msg
finally (return (values msg char))))
(defun echo-server (port &optional (log-stream *standard-output*))
(let ((connections (list (socket-listen "127.0.0.1" port :reuse-address t))))
(unwind-protect
(loop (loop for ready in (wait-for-input connections :ready-only t)
do (if (typep ready 'stream-server-usocket)
(push (socket-accept ready) connections)
(let* ((stream (socket-stream ready))
(msg (concatenate 'string "You said: " (read-all stream))))
(format log-stream "Got message...~%")
(write-string msg stream)
(socket-close ready)
(setf connections (remove ready connections))))))
(loop for c in connections do (loop while (socket-close c))))))
(echo-server 12321)
|
http://rosettacode.org/wiki/Elementary_cellular_automaton/Infinite_length | Elementary cellular automaton/Infinite length | The purpose of this task is to create a version of an Elementary cellular automaton whose number of cells is only limited by the memory size of the computer.
To be precise, consider the state of the automaton to be made of an infinite number of cells, but with a bounded support. In other words, to describe the state of the automaton, you need a finite number of adjacent cells, along with their individual state, and you then consider that the individual state of each of all other cells is the negation of the closest individual cell among the previously defined finite number of cells.
Examples:
1 -> ..., 0, 0, 1, 0, 0, ...
0, 1 -> ..., 1, 1, 0, 1, 0, 0, ...
1, 0, 1 -> ..., 0, 0, 1, 0, 1, 0, 0, ...
More complex methods can be imagined, provided it is possible to somehow encode the infinite sections. But for this task we will stick to this simple version.
| #Phix | Phix | with javascript_semantics
string s = ".#.",
t=s, r = "........"
integer rule = 18, k, l = length(s), w = 0
for i=1 to 8 do
r[i] = iff(mod(rule,2)?'#':'.')
rule = floor(rule/2)
end for
for i=0 to 25 do
?repeat(' ',floor((55-length(s))/2))&s
for j=1 to l do
k = (s[iff(j=1?l:j-1)]='#')*4
+ (s[ j ]='#')*2
+ (s[iff(j=l?1:j+1)]='#')+1
t[j] = r[k]
end for
if t[1]='#' then t = '.'&t end if
if t[$]='#' then t = t&'.' end if
l = length(t)
s = t
end for
|
http://rosettacode.org/wiki/EKG_sequence_convergence | EKG sequence convergence | The sequence is from the natural numbers and is defined by:
a(1) = 1;
a(2) = Start = 2;
for n > 2, a(n) shares at least one prime factor with a(n-1) and is the smallest such natural number not already used.
The sequence is called the EKG sequence (after its visual similarity to an electrocardiogram when graphed).
Variants of the sequence can be generated starting 1, N where N is any natural number larger than one. For the purposes of this task let us call:
The sequence described above , starting 1, 2, ... the EKG(2) sequence;
the sequence starting 1, 3, ... the EKG(3) sequence;
... the sequence starting 1, N, ... the EKG(N) sequence.
Convergence
If an algorithm that keeps track of the minimum amount of numbers and their corresponding prime factors used to generate the next term is used, then this may be known as the generators essential state. Two EKG generators with differing starts can converge to produce the same sequence after initial differences.
EKG(N1) and EKG(N2) are said to to have converged at and after generation a(c) if state_of(EKG(N1).a(c)) == state_of(EKG(N2).a(c)).
Task
Calculate and show here the first 10 members of EKG(2).
Calculate and show here the first 10 members of EKG(5).
Calculate and show here the first 10 members of EKG(7).
Calculate and show here the first 10 members of EKG(9).
Calculate and show here the first 10 members of EKG(10).
Calculate and show here at which term EKG(5) and EKG(7) converge (stretch goal).
Related Tasks
Greatest common divisor
Sieve of Eratosthenes
Reference
The EKG Sequence and the Tree of Numbers. (Video).
| #REXX | REXX | /*REXX program can generate and display several EKG sequences (with various starts).*/
parse arg nums start /*obtain optional arguments from the CL*/
if nums=='' | nums=="," then nums= 50 /*Not specified? Then use the default.*/
if start= '' | start= "," then start=2 5 7 9 10 /* " " " " " " */
do s=1 for words(start); $= /*step through the specified STARTs. */
second= word(start, s); say /*obtain the second integer in the seq.*/
do j=1 for nums
if j<3 then do; #=1; if j==2 then #=second; end /*handle 1st & 2nd number*/
else #= ekg(#)
$= $ right(#, max(2, length(#) ) ) /*append the EKG integer to the $ list.*/
end /*j*/ /* [↑] the RIGHT BIF aligns the numbers*/
say '(start' right(second, max(2, length(second) ) )"):"$ /*display EKG seq.*/
end /*s*/
exit /*stick a fork in it, we're all done. */
/*──────────────────────────────────────────────────────────────────────────────────────*/
add_: do while z//j == 0; z=z%j; _=_ j; w=w+1; end; return strip(_)
/*──────────────────────────────────────────────────────────────────────────────────────*/
ekg: procedure expose $; parse arg x 1 z,,_
w=0 /*W: number of factors.*/
do k=1 to 11 by 2; j=k; if j==1 then j=2 /*divide by low primes. */
if j==9 then iterate; call add_ /*skip ÷ 9; add to list.*/
end /*k*/
/*↓ skips multiples of 3*/
do y=0 by 2; j= j + 2 + y//4 /*increment J by 2 or 4.*/
parse var j '' -1 r; if r==5 then iterate /*divisible by five ? */
if j*j>x | j>z then leave /*passed the sqrt(x) ? */
_= add_() /*add a factor to list. */
end /*y*/
j=z; if z\==1 then _= add_() /*Z¬=1? Then add──►list.*/
if _='' then _=x /*Null? Then use prime. */
do j=3; done=1
do k=1 for w
if j // word(_, k)==0 then do; done=0; leave; end
end /*k*/
if done then iterate
if wordpos(j, $)==0 then return j /*return an EKG integer.*/
end /*j*/ |
http://rosettacode.org/wiki/Empty_string | Empty string | Languages may have features for dealing specifically with empty strings
(those containing no characters).
Task
Demonstrate how to assign an empty string to a variable.
Demonstrate how to check that a string is empty.
Demonstrate how to check that a string is not empty.
Other tasks related to string operations:
Metrics
Array length
String length
Copy a string
Empty string (assignment)
Counting
Word frequency
Letter frequency
Jewels and stones
I before E except after C
Bioinformatics/base count
Count occurrences of a substring
Count how many vowels and consonants occur in a string
Remove/replace
XXXX redacted
Conjugate a Latin verb
Remove vowels from a string
String interpolation (included)
Strip block comments
Strip comments from a string
Strip a set of characters from a string
Strip whitespace from a string -- top and tail
Strip control codes and extended characters from a string
Anagrams/Derangements/shuffling
Word wheel
ABC problem
Sattolo cycle
Knuth shuffle
Ordered words
Superpermutation minimisation
Textonyms (using a phone text pad)
Anagrams
Anagrams/Deranged anagrams
Permutations/Derangements
Find/Search/Determine
ABC words
Odd words
Word ladder
Semordnilap
Word search
Wordiff (game)
String matching
Tea cup rim text
Alternade words
Changeable words
State name puzzle
String comparison
Unique characters
Unique characters in each string
Extract file extension
Levenshtein distance
Palindrome detection
Common list elements
Longest common suffix
Longest common prefix
Compare a list of strings
Longest common substring
Find common directory path
Words from neighbour ones
Change e letters to i in words
Non-continuous subsequences
Longest common subsequence
Longest palindromic substrings
Longest increasing subsequence
Words containing "the" substring
Sum of the digits of n is substring of n
Determine if a string is numeric
Determine if a string is collapsible
Determine if a string is squeezable
Determine if a string has all unique characters
Determine if a string has all the same characters
Longest substrings without repeating characters
Find words which contains all the vowels
Find words which contains most consonants
Find words which contains more than 3 vowels
Find words which first and last three letters are equals
Find words which odd letters are consonants and even letters are vowels or vice_versa
Formatting
Substring
Rep-string
Word wrap
String case
Align columns
Literals/String
Repeat a string
Brace expansion
Brace expansion using ranges
Reverse a string
Phrase reversals
Comma quibbling
Special characters
String concatenation
Substring/Top and tail
Commatizing numbers
Reverse words in a string
Suffixation of decimal numbers
Long literals, with continuations
Numerical and alphabetical suffixes
Abbreviations, easy
Abbreviations, simple
Abbreviations, automatic
Song lyrics/poems/Mad Libs/phrases
Mad Libs
Magic 8-ball
99 Bottles of Beer
The Name Game (a song)
The Old lady swallowed a fly
The Twelve Days of Christmas
Tokenize
Text between
Tokenize a string
Word break problem
Tokenize a string with escaping
Split a character string based on change of character
Sequences
Show ASCII table
De Bruijn sequences
Self-referential sequences
Generate lower case ASCII alphabet
| #UNIX_Shell | UNIX Shell | # assign an empty string to a variable
s=""
# the "test" command can determine truth by examining the string itself
if [ "$s" ]; then echo "not empty"; else echo "empty"; fi
# compare the string to the empty string
if [ "$s" = "" ]; then echo "s is the empty string"; fi
if [ "$s" != "" ]; then echo "s is not empty"; fi
# examine the length of the string
if [ -z "$s" ]; then echo "the string has length zero: it is empty"; fi
if [ -n "$s" ]; then echo "the string has length non-zero: it is not empty"; fi |
http://rosettacode.org/wiki/Empty_string | Empty string | Languages may have features for dealing specifically with empty strings
(those containing no characters).
Task
Demonstrate how to assign an empty string to a variable.
Demonstrate how to check that a string is empty.
Demonstrate how to check that a string is not empty.
Other tasks related to string operations:
Metrics
Array length
String length
Copy a string
Empty string (assignment)
Counting
Word frequency
Letter frequency
Jewels and stones
I before E except after C
Bioinformatics/base count
Count occurrences of a substring
Count how many vowels and consonants occur in a string
Remove/replace
XXXX redacted
Conjugate a Latin verb
Remove vowels from a string
String interpolation (included)
Strip block comments
Strip comments from a string
Strip a set of characters from a string
Strip whitespace from a string -- top and tail
Strip control codes and extended characters from a string
Anagrams/Derangements/shuffling
Word wheel
ABC problem
Sattolo cycle
Knuth shuffle
Ordered words
Superpermutation minimisation
Textonyms (using a phone text pad)
Anagrams
Anagrams/Deranged anagrams
Permutations/Derangements
Find/Search/Determine
ABC words
Odd words
Word ladder
Semordnilap
Word search
Wordiff (game)
String matching
Tea cup rim text
Alternade words
Changeable words
State name puzzle
String comparison
Unique characters
Unique characters in each string
Extract file extension
Levenshtein distance
Palindrome detection
Common list elements
Longest common suffix
Longest common prefix
Compare a list of strings
Longest common substring
Find common directory path
Words from neighbour ones
Change e letters to i in words
Non-continuous subsequences
Longest common subsequence
Longest palindromic substrings
Longest increasing subsequence
Words containing "the" substring
Sum of the digits of n is substring of n
Determine if a string is numeric
Determine if a string is collapsible
Determine if a string is squeezable
Determine if a string has all unique characters
Determine if a string has all the same characters
Longest substrings without repeating characters
Find words which contains all the vowels
Find words which contains most consonants
Find words which contains more than 3 vowels
Find words which first and last three letters are equals
Find words which odd letters are consonants and even letters are vowels or vice_versa
Formatting
Substring
Rep-string
Word wrap
String case
Align columns
Literals/String
Repeat a string
Brace expansion
Brace expansion using ranges
Reverse a string
Phrase reversals
Comma quibbling
Special characters
String concatenation
Substring/Top and tail
Commatizing numbers
Reverse words in a string
Suffixation of decimal numbers
Long literals, with continuations
Numerical and alphabetical suffixes
Abbreviations, easy
Abbreviations, simple
Abbreviations, automatic
Song lyrics/poems/Mad Libs/phrases
Mad Libs
Magic 8-ball
99 Bottles of Beer
The Name Game (a song)
The Old lady swallowed a fly
The Twelve Days of Christmas
Tokenize
Text between
Tokenize a string
Word break problem
Tokenize a string with escaping
Split a character string based on change of character
Sequences
Show ASCII table
De Bruijn sequences
Self-referential sequences
Generate lower case ASCII alphabet
| #Ursa | Ursa | decl string s
set s ""
if (= s "")
out "empty" endl console
else
out "not empty" endl console
end if |
http://rosettacode.org/wiki/Empty_program | Empty program | Task
Create the simplest possible program that is still considered "correct."
| #Retro | Retro | |
http://rosettacode.org/wiki/Empty_program | Empty program | Task
Create the simplest possible program that is still considered "correct."
| #REXX | REXX | |
http://rosettacode.org/wiki/Empty_program | Empty program | Task
Create the simplest possible program that is still considered "correct."
| #Rhope | Rhope | Main(0,0)
|: :|
|
http://rosettacode.org/wiki/Element-wise_operations | Element-wise operations | This task is similar to:
Matrix multiplication
Matrix transposition
Task
Implement basic element-wise matrix-matrix and scalar-matrix operations, which can be referred to in other, higher-order tasks.
Implement:
addition
subtraction
multiplication
division
exponentiation
Extend the task if necessary to include additional basic operations, which should not require their own specialised task.
| #ALGOL_68 | ALGOL 68 | #!/usr/local/bin/a68g --script #
MODE SCALAR = REAL;
FORMAT scalar fmt = $g(0, 2)$;
MODE MATRIX = [3, 3]SCALAR;
FORMAT vector fmt = $"("n(2 UPB LOC MATRIX - 2 LWB LOC MATRIX)(f(scalar fmt)", ")f(scalar fmt)")"$;
FORMAT matrix fmt = $"("n(1 UPB LOC MATRIX - 1 LWB LOC MATRIX)(f(vector fmt)","l" ")f(vector fmt)")"$;
PROC elementwise op = (PROC(SCALAR, SCALAR)SCALAR op, MATRIX a, UNION(SCALAR, MATRIX) b)MATRIX: (
[LWB a:UPB a, 2 LWB a:2 UPB a]SCALAR out;
CASE b IN
(SCALAR b):
FOR i FROM LWB out TO UPB out DO
FOR j FROM 2 LWB out TO 2 UPB out DO
out[i, j]:=op(a[i, j], b)
OD
OD,
(MATRIX b):
FOR i FROM LWB out TO UPB out DO
FOR j FROM 2 LWB out TO 2 UPB out DO
out[i, j]:=op(a[i, j], b[i, j])
OD
OD
ESAC;
out
);
PROC plus = (SCALAR a, b)SCALAR: a+b,
minus = (SCALAR a, b)SCALAR: a-b,
times = (SCALAR a, b)SCALAR: a*b,
div = (SCALAR a, b)SCALAR: a/b,
pow = (SCALAR a, b)SCALAR: a**b;
main:(
SCALAR scalar := 10;
MATRIX matrix = (( 7, 11, 13),
(17, 19, 23),
(29, 31, 37));
printf(($f(matrix fmt)";"l$,
elementwise op(plus, matrix, scalar),
elementwise op(minus, matrix, scalar),
elementwise op(times, matrix, scalar),
elementwise op(div, matrix, scalar),
elementwise op(pow, matrix, scalar),
elementwise op(plus, matrix, matrix),
elementwise op(minus, matrix, matrix),
elementwise op(times, matrix, matrix),
elementwise op(div, matrix, matrix),
elementwise op(pow, matrix, matrix)
))
) |
http://rosettacode.org/wiki/Egyptian_division | Egyptian division | Egyptian division is a method of dividing integers using addition and
doubling that is similar to the algorithm of Ethiopian multiplication
Algorithm:
Given two numbers where the dividend is to be divided by the divisor:
Start the construction of a table of two columns: powers_of_2, and doublings; by a first row of a 1 (i.e. 2^0) in the first column and 1 times the divisor in the first row second column.
Create the second row with columns of 2 (i.e 2^1), and 2 * divisor in order.
Continue with successive i’th rows of 2^i and 2^i * divisor.
Stop adding rows, and keep only those rows, where 2^i * divisor is less than or equal to the dividend.
We now assemble two separate sums that both start as zero, called here answer and accumulator
Consider each row of the table, in the reverse order of its construction.
If the current value of the accumulator added to the doublings cell would be less than or equal to the dividend then add it to the accumulator, as well as adding the powers_of_2 cell value to the answer.
When the first row has been considered as above, then the integer division of dividend by divisor is given by answer.
(And the remainder is given by the absolute value of accumulator - dividend).
Example: 580 / 34
Table creation:
powers_of_2
doublings
1
34
2
68
4
136
8
272
16
544
Initialization of sums:
powers_of_2
doublings
answer
accumulator
1
34
2
68
4
136
8
272
16
544
0
0
Considering table rows, bottom-up:
When a row is considered it is shown crossed out if it is not accumulated, or bold if the row causes summations.
powers_of_2
doublings
answer
accumulator
1
34
2
68
4
136
8
272
16
544
16
544
powers_of_2
doublings
answer
accumulator
1
34
2
68
4
136
8
272
16
544
16
544
powers_of_2
doublings
answer
accumulator
1
34
2
68
4
136
16
544
8
272
16
544
powers_of_2
doublings
answer
accumulator
1
34
2
68
16
544
4
136
8
272
16
544
powers_of_2
doublings
answer
accumulator
1
34
17
578
2
68
4
136
8
272
16
544
Answer
So 580 divided by 34 using the Egyptian method is 17 remainder (578 - 580) or 2.
Task
The task is to create a function that does Egyptian division. The function should
closely follow the description above in using a list/array of powers of two, and
another of doublings.
Functions should be clear interpretations of the algorithm.
Use the function to divide 580 by 34 and show the answer here, on this page.
Related tasks
Egyptian fractions
References
Egyptian Number System
| #11l | 11l | F egyptian_divmod(dividend, divisor)
assert(divisor != 0)
V (pwrs, dbls) = ([1], [divisor])
L dbls.last <= dividend
pwrs.append(pwrs.last * 2)
dbls.append(pwrs.last * divisor)
V (ans, accum) = (0, 0)
L(pwr, dbl) zip(pwrs[((len)-2 ..).step(-1)], dbls[((len)-2 ..).step(-1)])
I accum + dbl <= dividend
accum += dbl
ans += pwr
R (ans, abs(accum - dividend))
L(i, j) cart_product(0.<13, 1..12)
assert(egyptian_divmod(i, j) == divmod(i, j))
V (i, j) = (580, 34)
V (d, m) = egyptian_divmod(i, j)
print(‘#. divided by #. using the Egyption method is #. remainder #.’.format(i, j, d, m)) |
http://rosettacode.org/wiki/Eertree | Eertree | An eertree is a data structure designed for efficient processing of certain palindrome tasks, for instance counting the number of sub-palindromes in an input string.
The data structure has commonalities to both tries and suffix trees.
See links below.
Task
Construct an eertree for the string "eertree", then output all sub-palindromes by traversing the tree.
See also
Wikipedia entry: trie.
Wikipedia entry: suffix tree
Cornell University Library, Computer Science, Data Structures and Algorithms ───► EERTREE: An Efficient Data Structure for Processing Palindromes in Strings.
| #Go | Go | package main
import "fmt"
func main() {
tree := eertree([]byte("eertree"))
fmt.Println(subPalindromes(tree))
}
type edges map[byte]int
type node struct {
length int
edges
suffix int
}
const evenRoot = 0
const oddRoot = 1
func eertree(s []byte) []node {
tree := []node{
evenRoot: {length: 0, suffix: oddRoot, edges: edges{}},
oddRoot: {length: -1, suffix: oddRoot, edges: edges{}},
}
suffix := oddRoot
var n, k int
for i, c := range s {
for n = suffix; ; n = tree[n].suffix {
k = tree[n].length
if b := i - k - 1; b >= 0 && s[b] == c {
break
}
}
if e, ok := tree[n].edges[c]; ok {
suffix = e
continue
}
suffix = len(tree)
tree = append(tree, node{length: k + 2, edges: edges{}})
tree[n].edges[c] = suffix
if tree[suffix].length == 1 {
tree[suffix].suffix = 0
continue
}
for {
n = tree[n].suffix
if b := i - tree[n].length - 1; b >= 0 && s[b] == c {
break
}
}
tree[suffix].suffix = tree[n].edges[c]
}
return tree
}
func subPalindromes(tree []node) (s []string) {
var children func(int, string)
children = func(n int, p string) {
for c, n := range tree[n].edges {
c := string(c)
p := c + p + c
s = append(s, p)
children(n, p)
}
}
children(0, "")
for c, n := range tree[1].edges {
c := string(c)
s = append(s, c)
children(n, c)
}
return
} |
http://rosettacode.org/wiki/Ethiopian_multiplication | Ethiopian multiplication | Ethiopian multiplication is a method of multiplying integers using only addition, doubling, and halving.
Method:
Take two numbers to be multiplied and write them down at the top of two columns.
In the left-hand column repeatedly halve the last number, discarding any remainders, and write the result below the last in the same column, until you write a value of 1.
In the right-hand column repeatedly double the last number and write the result below. stop when you add a result in the same row as where the left hand column shows 1.
Examine the table produced and discard any row where the value in the left column is even.
Sum the values in the right-hand column that remain to produce the result of multiplying the original two numbers together
For example: 17 × 34
17 34
Halving the first column:
17 34
8
4
2
1
Doubling the second column:
17 34
8 68
4 136
2 272
1 544
Strike-out rows whose first cell is even:
17 34
8 68
4 136
2 272
1 544
Sum the remaining numbers in the right-hand column:
17 34
8 --
4 ---
2 ---
1 544
====
578
So 17 multiplied by 34, by the Ethiopian method is 578.
Task
The task is to define three named functions/methods/procedures/subroutines:
one to halve an integer,
one to double an integer, and
one to state if an integer is even.
Use these functions to create a function that does Ethiopian multiplication.
References
Ethiopian multiplication explained (BBC Video clip)
A Night Of Numbers - Go Forth And Multiply (Video)
Russian Peasant Multiplication
Programming Praxis: Russian Peasant Multiplication
| #Plain_English | Plain English | \All required helper routines already exist in Plain English:
\
\To cut a number in half:
\Divide the number by 2.
\
\To double a number:
\Add the number to the number.
\
\To decide if a number is odd:
\Privatize the number.
\Bitwise and the number with 1.
\If the number is 0, say no.
\Say yes.
To run:
Start up.
Put 17 into a number.
Multiply the number by 34 (Ethiopian).
Convert the number to a string.
Write the string to the console.
Wait for the escape key.
Shut down.
To multiply a number by another number (Ethiopian):
Put 0 into a sum number.
Loop.
If the number is 0, break.
If the number is odd, add the other number to the sum.
Cut the number in half.
Double the other number.
Repeat.
Put the sum into the number. |
http://rosettacode.org/wiki/Elementary_cellular_automaton | Elementary cellular automaton | An elementary cellular automaton is a one-dimensional cellular automaton where there are two possible states (labeled 0 and 1) and the rule to determine the state of a cell in the next generation depends only on the current state of the cell and its two immediate neighbors. Those three values can be encoded with three bits.
The rules of evolution are then encoded with eight bits indicating the outcome of each of the eight possibilities 111, 110, 101, 100, 011, 010, 001 and 000 in this order. Thus for instance the rule 13 means that a state is updated to 1 only in the cases 011, 010 and 000, since 13 in binary is 0b00001101.
Task
Create a subroutine, program or function that allows to create and visualize the evolution of any of the 256 possible elementary cellular automaton of arbitrary space length and for any given initial state. You can demonstrate your solution with any automaton of your choice.
The space state should wrap: this means that the left-most cell should be considered as the right neighbor of the right-most cell, and reciprocally.
This task is basically a generalization of one-dimensional cellular automata.
See also
Cellular automata (natureofcode.com)
| #C | C | #include <stdio.h>
#include <limits.h>
typedef unsigned long long ull;
#define N (sizeof(ull) * CHAR_BIT)
#define B(x) (1ULL << (x))
void evolve(ull state, int rule)
{
int i;
ull st;
printf("Rule %d:\n", rule);
do {
st = state;
for (i = N; i--; ) putchar(st & B(i) ? '#' : '.');
putchar('\n');
for (state = i = 0; i < N; i++)
if (rule & B(7 & (st>>(i-1) | st<<(N+1-i))))
state |= B(i);
} while (st != state);
}
int main(int argc, char **argv)
{
evolve(B(N/2), 90);
evolve(B(N/4)|B(N - N/4), 30); // well, enjoy the fireworks
return 0;
} |
http://rosettacode.org/wiki/Factorial | Factorial | Definitions
The factorial of 0 (zero) is defined as being 1 (unity).
The Factorial Function of a positive integer, n, is defined as the product of the sequence:
n, n-1, n-2, ... 1
Task
Write a function to return the factorial of a number.
Solutions can be iterative or recursive.
Support for trapping negative n errors is optional.
Related task
Primorial numbers
| #Standard_ML | Standard ML | fun factorial n =
if n <= 0 then 1
else n * factorial (n-1) |
http://rosettacode.org/wiki/Even_or_odd | Even or odd | Task
Test whether an integer is even or odd.
There is more than one way to solve this task:
Use the even and odd predicates, if the language provides them.
Check the least significant digit. With binary integers, i bitwise-and 1 equals 0 iff i is even, or equals 1 iff i is odd.
Divide i by 2. The remainder equals 0 iff i is even. The remainder equals +1 or -1 iff i is odd.
Use modular congruences:
i ≡ 0 (mod 2) iff i is even.
i ≡ 1 (mod 2) iff i is odd.
| #SSEM | SSEM | 11110000000000100000000000000000 0. -15 to c
00000000000000110000000000000000 1. Test
11110000000001100000000000000000 2. c to 15
11110000000000100000000000000000 3. -15 to c
00001000000001100000000000000000 4. c to 16
00001000000000100000000000000000 5. -16 to c
01110000000000010000000000000000 6. Sub. 14
11110000000001100000000000000000 7. c to 15
10110000000000010000000000000000 8. Sub. 13
00000000000000110000000000000000 9. Test
01110000000000000000000000000000 10. 14 to CI
11110000000000100000000000000000 11. -15 to c
00000000000001110000000000000000 12. Stop
10000000000000000000000000000000 13. 1
01000000000000000000000000000000 14. 2 |
http://rosettacode.org/wiki/Even_or_odd | Even or odd | Task
Test whether an integer is even or odd.
There is more than one way to solve this task:
Use the even and odd predicates, if the language provides them.
Check the least significant digit. With binary integers, i bitwise-and 1 equals 0 iff i is even, or equals 1 iff i is odd.
Divide i by 2. The remainder equals 0 iff i is even. The remainder equals +1 or -1 iff i is odd.
Use modular congruences:
i ≡ 0 (mod 2) iff i is even.
i ≡ 1 (mod 2) iff i is odd.
| #Standard_ML | Standard ML | fun even n =
n mod 2 = 0;
fun odd n =
n mod 2 <> 0;
(* bitwise and *)
type werd = Word.word;
fun evenbitw(w: werd) =
Word.andb(w, 0w2) = 0w0;
fun oddbitw(w: werd) =
Word.andb(w, 0w2) <> 0w0; |
http://rosettacode.org/wiki/Echo_server | Echo server | Create a network service that sits on TCP port 12321, which accepts connections on that port, and which echoes complete lines (using a carriage-return/line-feed sequence as line separator) back to clients. No error handling is required. For the purposes of testing, it is only necessary to support connections from localhost (127.0.0.1 or perhaps ::1). Logging of connection information to standard output is recommended.
The implementation must be able to handle simultaneous connections from multiple clients. A multi-threaded or multi-process solution may be used. Each connection must be able to echo more than a single line.
The implementation must not stop responding to other clients if one client sends a partial line or stops reading responses.
| #D | D | import std.array, std.socket;
void main() {
auto listener = new TcpSocket;
assert(listener.isAlive);
listener.bind(new InternetAddress(12321));
listener.listen(10);
Socket currSock;
uint bytesRead;
ubyte[1] buff;
while (true) {
currSock = listener.accept();
while ((bytesRead = currSock.receive(buff)) > 0)
currSock.send(buff);
currSock.close();
buff.clear();
}
} |
http://rosettacode.org/wiki/Elementary_cellular_automaton/Infinite_length | Elementary cellular automaton/Infinite length | The purpose of this task is to create a version of an Elementary cellular automaton whose number of cells is only limited by the memory size of the computer.
To be precise, consider the state of the automaton to be made of an infinite number of cells, but with a bounded support. In other words, to describe the state of the automaton, you need a finite number of adjacent cells, along with their individual state, and you then consider that the individual state of each of all other cells is the negation of the closest individual cell among the previously defined finite number of cells.
Examples:
1 -> ..., 0, 0, 1, 0, 0, ...
0, 1 -> ..., 1, 1, 0, 1, 0, 0, ...
1, 0, 1 -> ..., 0, 0, 1, 0, 1, 0, 0, ...
More complex methods can be imagined, provided it is possible to somehow encode the infinite sections. But for this task we will stick to this simple version.
| #Python | Python | def _notcell(c):
return '0' if c == '1' else '1'
def eca_infinite(cells, rule):
lencells = len(cells)
rulebits = '{0:08b}'.format(rule)
neighbours2next = {'{0:03b}'.format(n):rulebits[::-1][n] for n in range(8)}
c = cells
while True:
yield c
c = _notcell(c[0])*2 + c + _notcell(c[-1])*2 # Extend and pad the ends
c = ''.join(neighbours2next[c[i-1:i+2]] for i in range(1,len(c) - 1))
#yield c[1:-1]
if __name__ == '__main__':
lines = 25
for rule in (90, 30):
print('\nRule: %i' % rule)
for i, c in zip(range(lines), eca_infinite('1', rule)):
print('%2i: %s%s' % (i, ' '*(lines - i), c.replace('0', '.').replace('1', '#'))) |
http://rosettacode.org/wiki/Elementary_cellular_automaton/Infinite_length | Elementary cellular automaton/Infinite length | The purpose of this task is to create a version of an Elementary cellular automaton whose number of cells is only limited by the memory size of the computer.
To be precise, consider the state of the automaton to be made of an infinite number of cells, but with a bounded support. In other words, to describe the state of the automaton, you need a finite number of adjacent cells, along with their individual state, and you then consider that the individual state of each of all other cells is the negation of the closest individual cell among the previously defined finite number of cells.
Examples:
1 -> ..., 0, 0, 1, 0, 0, ...
0, 1 -> ..., 1, 1, 0, 1, 0, 0, ...
1, 0, 1 -> ..., 0, 0, 1, 0, 1, 0, 0, ...
More complex methods can be imagined, provided it is possible to somehow encode the infinite sections. But for this task we will stick to this simple version.
| #Racket | Racket | #lang racket
; below is the code from the parent task
(require "Elementary_cellular_automata.rkt")
(require racket/fixnum)
(define (wrap-rule-infinite v-in vl-1 offset)
(define l-bit-set? (bitwise-bit-set? (fxvector-ref v-in 0) usable-bits/fixnum-1))
(define r-bit-set? (bitwise-bit-set? (fxvector-ref v-in vl-1) 0))
;; if we need to extend left offset is reduced by 1
(define l-pad-words (if l-bit-set? 1 0))
(define r-pad-words (if r-bit-set? 1 0))
(define new-words (fx+ l-pad-words r-pad-words))
(cond
[(fx= 0 new-words) (values v-in vl-1 offset)] ; nothing changes
[else
(define offset- (if l-bit-set? (fx- offset 1) offset))
(define l-sequence (if l-bit-set? (in-value 0) (in-sequences)))
(define vl-1+ (fx+ vl-1 (fx+ l-pad-words r-pad-words)))
(define v-out
(for/fxvector
#:length (fx+ vl-1+ 1) #:fill 0 ; right padding
([f (in-sequences l-sequence (in-fxvector v-in))])
f))
(values v-out vl-1+ offset-)]))
(module+ main
(define ng/90/infinite (CA-next-generation 90 #:wrap-rule wrap-rule-infinite))
(for/fold ([v (fxvector #b10000000000000000000)]
[o 1]) ; start by pushing output right by one
([step (in-range 40)])
(show-automaton v #:step step #:push-right o)
(newline)
(ng/90/infinite v o))) |
http://rosettacode.org/wiki/EKG_sequence_convergence | EKG sequence convergence | The sequence is from the natural numbers and is defined by:
a(1) = 1;
a(2) = Start = 2;
for n > 2, a(n) shares at least one prime factor with a(n-1) and is the smallest such natural number not already used.
The sequence is called the EKG sequence (after its visual similarity to an electrocardiogram when graphed).
Variants of the sequence can be generated starting 1, N where N is any natural number larger than one. For the purposes of this task let us call:
The sequence described above , starting 1, 2, ... the EKG(2) sequence;
the sequence starting 1, 3, ... the EKG(3) sequence;
... the sequence starting 1, N, ... the EKG(N) sequence.
Convergence
If an algorithm that keeps track of the minimum amount of numbers and their corresponding prime factors used to generate the next term is used, then this may be known as the generators essential state. Two EKG generators with differing starts can converge to produce the same sequence after initial differences.
EKG(N1) and EKG(N2) are said to to have converged at and after generation a(c) if state_of(EKG(N1).a(c)) == state_of(EKG(N2).a(c)).
Task
Calculate and show here the first 10 members of EKG(2).
Calculate and show here the first 10 members of EKG(5).
Calculate and show here the first 10 members of EKG(7).
Calculate and show here the first 10 members of EKG(9).
Calculate and show here the first 10 members of EKG(10).
Calculate and show here at which term EKG(5) and EKG(7) converge (stretch goal).
Related Tasks
Greatest common divisor
Sieve of Eratosthenes
Reference
The EKG Sequence and the Tree of Numbers. (Video).
| #Sidef | Sidef | class Seq(terms, callback) {
method next {
terms += callback(terms)
}
method nth(n) {
while (terms.len < n) {
self.next
}
terms[n-1]
}
method first(n) {
while (terms.len < n) {
self.next
}
terms.first(n)
}
}
func next_EKG (s) {
2..Inf -> first {|k|
!(s.contains(k) || s[-1].is_coprime(k))
}
}
func EKG (start) {
Seq([1, start], next_EKG)
}
func converge_at(ints) {
var ekgs = ints.map(EKG)
2..Inf -> first {|k|
(ekgs.map { .nth(k) }.uniq.len == 1) &&
(ekgs.map { .first(k).sort }.uniq.len == 1)
}
}
for k in [2, 5, 7, 9, 10] {
say "EKG(#{k}) = #{EKG(k).first(10)}"
}
for arr in [[5,7], [2, 5, 7, 9, 10]] {
var c = converge_at(arr)
say "EKGs of #{arr} converge at term #{c}"
} |
http://rosettacode.org/wiki/Empty_string | Empty string | Languages may have features for dealing specifically with empty strings
(those containing no characters).
Task
Demonstrate how to assign an empty string to a variable.
Demonstrate how to check that a string is empty.
Demonstrate how to check that a string is not empty.
Other tasks related to string operations:
Metrics
Array length
String length
Copy a string
Empty string (assignment)
Counting
Word frequency
Letter frequency
Jewels and stones
I before E except after C
Bioinformatics/base count
Count occurrences of a substring
Count how many vowels and consonants occur in a string
Remove/replace
XXXX redacted
Conjugate a Latin verb
Remove vowels from a string
String interpolation (included)
Strip block comments
Strip comments from a string
Strip a set of characters from a string
Strip whitespace from a string -- top and tail
Strip control codes and extended characters from a string
Anagrams/Derangements/shuffling
Word wheel
ABC problem
Sattolo cycle
Knuth shuffle
Ordered words
Superpermutation minimisation
Textonyms (using a phone text pad)
Anagrams
Anagrams/Deranged anagrams
Permutations/Derangements
Find/Search/Determine
ABC words
Odd words
Word ladder
Semordnilap
Word search
Wordiff (game)
String matching
Tea cup rim text
Alternade words
Changeable words
State name puzzle
String comparison
Unique characters
Unique characters in each string
Extract file extension
Levenshtein distance
Palindrome detection
Common list elements
Longest common suffix
Longest common prefix
Compare a list of strings
Longest common substring
Find common directory path
Words from neighbour ones
Change e letters to i in words
Non-continuous subsequences
Longest common subsequence
Longest palindromic substrings
Longest increasing subsequence
Words containing "the" substring
Sum of the digits of n is substring of n
Determine if a string is numeric
Determine if a string is collapsible
Determine if a string is squeezable
Determine if a string has all unique characters
Determine if a string has all the same characters
Longest substrings without repeating characters
Find words which contains all the vowels
Find words which contains most consonants
Find words which contains more than 3 vowels
Find words which first and last three letters are equals
Find words which odd letters are consonants and even letters are vowels or vice_versa
Formatting
Substring
Rep-string
Word wrap
String case
Align columns
Literals/String
Repeat a string
Brace expansion
Brace expansion using ranges
Reverse a string
Phrase reversals
Comma quibbling
Special characters
String concatenation
Substring/Top and tail
Commatizing numbers
Reverse words in a string
Suffixation of decimal numbers
Long literals, with continuations
Numerical and alphabetical suffixes
Abbreviations, easy
Abbreviations, simple
Abbreviations, automatic
Song lyrics/poems/Mad Libs/phrases
Mad Libs
Magic 8-ball
99 Bottles of Beer
The Name Game (a song)
The Old lady swallowed a fly
The Twelve Days of Christmas
Tokenize
Text between
Tokenize a string
Word break problem
Tokenize a string with escaping
Split a character string based on change of character
Sequences
Show ASCII table
De Bruijn sequences
Self-referential sequences
Generate lower case ASCII alphabet
| #VAX_Assembly | VAX Assembly | desc: .ascid "not empty" ;descriptor (len+addr) and text
.entry empty, ^m<>
tstw desc ;check length field
beql is_empty
;... not empty
clrw desc ;set length to zero -> empty
is_empty:
;... empty
ret
.end empty |
http://rosettacode.org/wiki/Empty_string | Empty string | Languages may have features for dealing specifically with empty strings
(those containing no characters).
Task
Demonstrate how to assign an empty string to a variable.
Demonstrate how to check that a string is empty.
Demonstrate how to check that a string is not empty.
Other tasks related to string operations:
Metrics
Array length
String length
Copy a string
Empty string (assignment)
Counting
Word frequency
Letter frequency
Jewels and stones
I before E except after C
Bioinformatics/base count
Count occurrences of a substring
Count how many vowels and consonants occur in a string
Remove/replace
XXXX redacted
Conjugate a Latin verb
Remove vowels from a string
String interpolation (included)
Strip block comments
Strip comments from a string
Strip a set of characters from a string
Strip whitespace from a string -- top and tail
Strip control codes and extended characters from a string
Anagrams/Derangements/shuffling
Word wheel
ABC problem
Sattolo cycle
Knuth shuffle
Ordered words
Superpermutation minimisation
Textonyms (using a phone text pad)
Anagrams
Anagrams/Deranged anagrams
Permutations/Derangements
Find/Search/Determine
ABC words
Odd words
Word ladder
Semordnilap
Word search
Wordiff (game)
String matching
Tea cup rim text
Alternade words
Changeable words
State name puzzle
String comparison
Unique characters
Unique characters in each string
Extract file extension
Levenshtein distance
Palindrome detection
Common list elements
Longest common suffix
Longest common prefix
Compare a list of strings
Longest common substring
Find common directory path
Words from neighbour ones
Change e letters to i in words
Non-continuous subsequences
Longest common subsequence
Longest palindromic substrings
Longest increasing subsequence
Words containing "the" substring
Sum of the digits of n is substring of n
Determine if a string is numeric
Determine if a string is collapsible
Determine if a string is squeezable
Determine if a string has all unique characters
Determine if a string has all the same characters
Longest substrings without repeating characters
Find words which contains all the vowels
Find words which contains most consonants
Find words which contains more than 3 vowels
Find words which first and last three letters are equals
Find words which odd letters are consonants and even letters are vowels or vice_versa
Formatting
Substring
Rep-string
Word wrap
String case
Align columns
Literals/String
Repeat a string
Brace expansion
Brace expansion using ranges
Reverse a string
Phrase reversals
Comma quibbling
Special characters
String concatenation
Substring/Top and tail
Commatizing numbers
Reverse words in a string
Suffixation of decimal numbers
Long literals, with continuations
Numerical and alphabetical suffixes
Abbreviations, easy
Abbreviations, simple
Abbreviations, automatic
Song lyrics/poems/Mad Libs/phrases
Mad Libs
Magic 8-ball
99 Bottles of Beer
The Name Game (a song)
The Old lady swallowed a fly
The Twelve Days of Christmas
Tokenize
Text between
Tokenize a string
Word break problem
Tokenize a string with escaping
Split a character string based on change of character
Sequences
Show ASCII table
De Bruijn sequences
Self-referential sequences
Generate lower case ASCII alphabet
| #VBA | VBA |
dim s as string
' assign an empty string to a variable (six bytes):
s = ""
' assign null string pointer to a variable (zero bytes, according to RubberduckVBA):
s = vbNullString
' if your VBA code interacts with non-VBA code, this difference may become significant!
' test if a string is empty:
if s = "" then Debug.Print "empty!"
' or:
if Len(s) = 0 then Debug.Print "still empty!"
'test if a string is not empty:
if s <> "" then Debug.Print "not an empty string"
'or:
if Len(s) > 0 then Debug.Print "not empty."
|
http://rosettacode.org/wiki/Empty_program | Empty program | Task
Create the simplest possible program that is still considered "correct."
| #Ring | Ring | |
http://rosettacode.org/wiki/Empty_program | Empty program | Task
Create the simplest possible program that is still considered "correct."
| #Robotic | Robotic | |
http://rosettacode.org/wiki/Empty_program | Empty program | Task
Create the simplest possible program that is still considered "correct."
| #Ruby | Ruby | #!/usr/bin/env ruby |
http://rosettacode.org/wiki/Element-wise_operations | Element-wise operations | This task is similar to:
Matrix multiplication
Matrix transposition
Task
Implement basic element-wise matrix-matrix and scalar-matrix operations, which can be referred to in other, higher-order tasks.
Implement:
addition
subtraction
multiplication
division
exponentiation
Extend the task if necessary to include additional basic operations, which should not require their own specialised task.
| #Amazing_Hopper | Amazing Hopper |
#include <hopper.h>
main:
/* create an integer random array */
A=-1,{10}rand array(A), mulby(10), ceil, mov(A)
{","}tok sep
{"\ENF","ORIGINAL ARRAY :",A,"\OFF\n","="}reply(90),
println
{"Increment :\t"}, ++A,{A} println
{"Decrement :\t"}, --A,{A} println
{"post Increment: "}, A++, println
{*"\t",A} println
{"post Decrement: "}, A--, println
{*"\t",A} println
{"A + 5 :\t\t"}, {A} plus (5), println
{"5 + A :\t\t"}, {5} plus (A), println
{"A - 5 :\t\t"}, {A} minus (5), println
{"5 - A :\t\t"}, {5} minus (A), println
{"A * 5 :\t\t"}, {A} mul by (5), println
{"5 * A :\t\t"}, {5} mul by (A), println
{"A / 5 :\t\t"}, {A} div by (5), println
{"5 / A :\t\t"}, {5} div by (A), println
{"A \ 5 :\t\t"}, {A} idiv by (5), println
{"5 \ A :\t\t"}, {5} idiv by (A), println
{"A ^ 5 :\t\t"}, {A} pow by (5), println
{"5 ^ A :\t\t"}, {5} pow by (A), println
{"A % 5 :\t\t"}, {A} module (5), println
{"5 % A :\t\t"}, {5} module (A), println
{"SQRT(A) + 5:\t"}, {A} sqrt, plus(5),
tmp=0,cpy(tmp), println
{"--> CEIL :\t"} {tmp},ceil, println
{"--> FLOOR :\t"} {tmp},floor, println
{"A + A :\t\t"}, {A} plus (A), println
{"A - A :\t\t"}, {A} minus (A), println
{"A * A :\t\t"}, {A} mulby (A), println
{"A / A :\t\t"}, {A} div by (A), println
{"A \ A :\t\t"}, {A} idiv by (A), println
{"A ^ A :\t\t"}, {A} pow by (A), println
{"A % A :\t\t"}, {A} module (A), println
{"Etcetera...\n"}, println
exit(0)
|
http://rosettacode.org/wiki/Egyptian_division | Egyptian division | Egyptian division is a method of dividing integers using addition and
doubling that is similar to the algorithm of Ethiopian multiplication
Algorithm:
Given two numbers where the dividend is to be divided by the divisor:
Start the construction of a table of two columns: powers_of_2, and doublings; by a first row of a 1 (i.e. 2^0) in the first column and 1 times the divisor in the first row second column.
Create the second row with columns of 2 (i.e 2^1), and 2 * divisor in order.
Continue with successive i’th rows of 2^i and 2^i * divisor.
Stop adding rows, and keep only those rows, where 2^i * divisor is less than or equal to the dividend.
We now assemble two separate sums that both start as zero, called here answer and accumulator
Consider each row of the table, in the reverse order of its construction.
If the current value of the accumulator added to the doublings cell would be less than or equal to the dividend then add it to the accumulator, as well as adding the powers_of_2 cell value to the answer.
When the first row has been considered as above, then the integer division of dividend by divisor is given by answer.
(And the remainder is given by the absolute value of accumulator - dividend).
Example: 580 / 34
Table creation:
powers_of_2
doublings
1
34
2
68
4
136
8
272
16
544
Initialization of sums:
powers_of_2
doublings
answer
accumulator
1
34
2
68
4
136
8
272
16
544
0
0
Considering table rows, bottom-up:
When a row is considered it is shown crossed out if it is not accumulated, or bold if the row causes summations.
powers_of_2
doublings
answer
accumulator
1
34
2
68
4
136
8
272
16
544
16
544
powers_of_2
doublings
answer
accumulator
1
34
2
68
4
136
8
272
16
544
16
544
powers_of_2
doublings
answer
accumulator
1
34
2
68
4
136
16
544
8
272
16
544
powers_of_2
doublings
answer
accumulator
1
34
2
68
16
544
4
136
8
272
16
544
powers_of_2
doublings
answer
accumulator
1
34
17
578
2
68
4
136
8
272
16
544
Answer
So 580 divided by 34 using the Egyptian method is 17 remainder (578 - 580) or 2.
Task
The task is to create a function that does Egyptian division. The function should
closely follow the description above in using a list/array of powers of two, and
another of doublings.
Functions should be clear interpretations of the algorithm.
Use the function to divide 580 by 34 and show the answer here, on this page.
Related tasks
Egyptian fractions
References
Egyptian Number System
| #Action.21 | Action! | TYPE Answer=[CARD result,reminder]
PROC EgyptianDivision(CARD dividend,divisor Answer POINTER res)
DEFINE SIZE="16"
CARD ARRAY powers(SIZE),doublings(SIZE)
CARD power,doubling,accumulator
INT i,count
count=0 power=1 doubling=divisor
WHILE count<SIZE AND doubling<=dividend
DO
powers(count)=power
doublings(count)=doubling
count==+1
power==LSH 1
doubling==LSH 1
OD
i=count-1
res.result=0
accumulator=0
WHILE i>=0
DO
IF accumulator+doublings(i)<=dividend THEN
accumulator==+doublings(i)
res.result==+powers(i)
FI
i==-1
OD
res.reminder=dividend-accumulator
RETURN
PROC Main()
CARD dividend=[580],divisor=[34]
Answer res
EgyptianDivision(dividend,divisor,res)
PrintF("%U / %U = %U reminder %U",dividend,divisor,res.result,res.reminder)
RETURN |
http://rosettacode.org/wiki/Egyptian_division | Egyptian division | Egyptian division is a method of dividing integers using addition and
doubling that is similar to the algorithm of Ethiopian multiplication
Algorithm:
Given two numbers where the dividend is to be divided by the divisor:
Start the construction of a table of two columns: powers_of_2, and doublings; by a first row of a 1 (i.e. 2^0) in the first column and 1 times the divisor in the first row second column.
Create the second row with columns of 2 (i.e 2^1), and 2 * divisor in order.
Continue with successive i’th rows of 2^i and 2^i * divisor.
Stop adding rows, and keep only those rows, where 2^i * divisor is less than or equal to the dividend.
We now assemble two separate sums that both start as zero, called here answer and accumulator
Consider each row of the table, in the reverse order of its construction.
If the current value of the accumulator added to the doublings cell would be less than or equal to the dividend then add it to the accumulator, as well as adding the powers_of_2 cell value to the answer.
When the first row has been considered as above, then the integer division of dividend by divisor is given by answer.
(And the remainder is given by the absolute value of accumulator - dividend).
Example: 580 / 34
Table creation:
powers_of_2
doublings
1
34
2
68
4
136
8
272
16
544
Initialization of sums:
powers_of_2
doublings
answer
accumulator
1
34
2
68
4
136
8
272
16
544
0
0
Considering table rows, bottom-up:
When a row is considered it is shown crossed out if it is not accumulated, or bold if the row causes summations.
powers_of_2
doublings
answer
accumulator
1
34
2
68
4
136
8
272
16
544
16
544
powers_of_2
doublings
answer
accumulator
1
34
2
68
4
136
8
272
16
544
16
544
powers_of_2
doublings
answer
accumulator
1
34
2
68
4
136
16
544
8
272
16
544
powers_of_2
doublings
answer
accumulator
1
34
2
68
16
544
4
136
8
272
16
544
powers_of_2
doublings
answer
accumulator
1
34
17
578
2
68
4
136
8
272
16
544
Answer
So 580 divided by 34 using the Egyptian method is 17 remainder (578 - 580) or 2.
Task
The task is to create a function that does Egyptian division. The function should
closely follow the description above in using a list/array of powers of two, and
another of doublings.
Functions should be clear interpretations of the algorithm.
Use the function to divide 580 by 34 and show the answer here, on this page.
Related tasks
Egyptian fractions
References
Egyptian Number System
| #Ada | Ada |
with Ada.Text_IO;
procedure Egyptian_Division is
procedure Divide (a : Natural; b : Positive; q, r : out Natural) is
doublings : array (0..31) of Natural; -- The natural type holds values < 2^32 so no need going beyond
m, sum, last_index_touched : Natural := 0;
begin
for i in doublings'Range loop
m := b * 2**i;
exit when m > a ;
doublings (i) := m;
last_index_touched := i;
end loop;
q := 0;
for i in reverse doublings'First .. last_index_touched loop
m := sum + doublings (i);
if m <= a then
sum := m;
q := q + 2**i;
end if;
end loop;
r := a -sum;
end Divide;
q, r : Natural;
begin
Divide (580,34, q, r);
Ada.Text_IO.put_line ("Quotient="&q'Img & " Remainder="&r'img);
end Egyptian_Division;
|
http://rosettacode.org/wiki/Eertree | Eertree | An eertree is a data structure designed for efficient processing of certain palindrome tasks, for instance counting the number of sub-palindromes in an input string.
The data structure has commonalities to both tries and suffix trees.
See links below.
Task
Construct an eertree for the string "eertree", then output all sub-palindromes by traversing the tree.
See also
Wikipedia entry: trie.
Wikipedia entry: suffix tree
Cornell University Library, Computer Science, Data Structures and Algorithms ───► EERTREE: An Efficient Data Structure for Processing Palindromes in Strings.
| #Java | Java | import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
public class Eertree {
public static void main(String[] args) {
List<Node> tree = eertree("eertree");
List<String> result = subPalindromes(tree);
System.out.println(result);
}
private static class Node {
int length;
Map<Character, Integer> edges = new HashMap<>();
int suffix;
public Node(int length) {
this.length = length;
}
public Node(int length, Map<Character, Integer> edges, int suffix) {
this.length = length;
this.edges = edges != null ? edges : new HashMap<>();
this.suffix = suffix;
}
}
private static final int EVEN_ROOT = 0;
private static final int ODD_ROOT = 1;
private static List<Node> eertree(String s) {
List<Node> tree = new ArrayList<>();
tree.add(new Node(0, null, ODD_ROOT));
tree.add(new Node(-1, null, ODD_ROOT));
int suffix = ODD_ROOT;
int n, k;
for (int i = 0; i < s.length(); ++i) {
char c = s.charAt(i);
for (n = suffix; ; n = tree.get(n).suffix) {
k = tree.get(n).length;
int b = i - k - 1;
if (b >= 0 && s.charAt(b) == c) {
break;
}
}
if (tree.get(n).edges.containsKey(c)) {
suffix = tree.get(n).edges.get(c);
continue;
}
suffix = tree.size();
tree.add(new Node(k + 2));
tree.get(n).edges.put(c, suffix);
if (tree.get(suffix).length == 1) {
tree.get(suffix).suffix = 0;
continue;
}
while (true) {
n = tree.get(n).suffix;
int b = i - tree.get(n).length - 1;
if (b >= 0 && s.charAt(b) == c) {
break;
}
}
tree.get(suffix).suffix = tree.get(n).edges.get(c);
}
return tree;
}
private static List<String> subPalindromes(List<Node> tree) {
List<String> s = new ArrayList<>();
subPalindromes_children(0, "", tree, s);
for (Map.Entry<Character, Integer> cm : tree.get(1).edges.entrySet()) {
String ct = String.valueOf(cm.getKey());
s.add(ct);
subPalindromes_children(cm.getValue(), ct, tree, s);
}
return s;
}
// nested methods are a pain, even if lambdas make that possible for Java
private static void subPalindromes_children(final int n, final String p, final List<Node> tree, List<String> s) {
for (Map.Entry<Character, Integer> cm : tree.get(n).edges.entrySet()) {
Character c = cm.getKey();
Integer m = cm.getValue();
String pl = c + p + c;
s.add(pl);
subPalindromes_children(m, pl, tree, s);
}
}
} |
http://rosettacode.org/wiki/Ethiopian_multiplication | Ethiopian multiplication | Ethiopian multiplication is a method of multiplying integers using only addition, doubling, and halving.
Method:
Take two numbers to be multiplied and write them down at the top of two columns.
In the left-hand column repeatedly halve the last number, discarding any remainders, and write the result below the last in the same column, until you write a value of 1.
In the right-hand column repeatedly double the last number and write the result below. stop when you add a result in the same row as where the left hand column shows 1.
Examine the table produced and discard any row where the value in the left column is even.
Sum the values in the right-hand column that remain to produce the result of multiplying the original two numbers together
For example: 17 × 34
17 34
Halving the first column:
17 34
8
4
2
1
Doubling the second column:
17 34
8 68
4 136
2 272
1 544
Strike-out rows whose first cell is even:
17 34
8 68
4 136
2 272
1 544
Sum the remaining numbers in the right-hand column:
17 34
8 --
4 ---
2 ---
1 544
====
578
So 17 multiplied by 34, by the Ethiopian method is 578.
Task
The task is to define three named functions/methods/procedures/subroutines:
one to halve an integer,
one to double an integer, and
one to state if an integer is even.
Use these functions to create a function that does Ethiopian multiplication.
References
Ethiopian multiplication explained (BBC Video clip)
A Night Of Numbers - Go Forth And Multiply (Video)
Russian Peasant Multiplication
Programming Praxis: Russian Peasant Multiplication
| #Powerbuilder | Powerbuilder | public function boolean wf_iseven (long al_arg);return mod(al_arg, 2 ) = 0
end function
public function long wf_halve (long al_arg);RETURN int(al_arg / 2)
end function
public function long wf_double (long al_arg);RETURN al_arg * 2
end function
public function long wf_ethiopianmultiplication (long al_multiplicand, long al_multiplier);// calculate result
long ll_product
DO WHILE al_multiplicand >= 1
IF wf_iseven(al_multiplicand) THEN
// do nothing
ELSE
ll_product += al_multiplier
END IF
al_multiplicand = wf_halve(al_multiplicand)
al_multiplier = wf_double(al_multiplier)
LOOP
return ll_product
end function
// example call
long ll_answer
ll_answer = wf_ethiopianmultiplication(17,34) |
http://rosettacode.org/wiki/Elementary_cellular_automaton | Elementary cellular automaton | An elementary cellular automaton is a one-dimensional cellular automaton where there are two possible states (labeled 0 and 1) and the rule to determine the state of a cell in the next generation depends only on the current state of the cell and its two immediate neighbors. Those three values can be encoded with three bits.
The rules of evolution are then encoded with eight bits indicating the outcome of each of the eight possibilities 111, 110, 101, 100, 011, 010, 001 and 000 in this order. Thus for instance the rule 13 means that a state is updated to 1 only in the cases 011, 010 and 000, since 13 in binary is 0b00001101.
Task
Create a subroutine, program or function that allows to create and visualize the evolution of any of the 256 possible elementary cellular automaton of arbitrary space length and for any given initial state. You can demonstrate your solution with any automaton of your choice.
The space state should wrap: this means that the left-most cell should be considered as the right neighbor of the right-most cell, and reciprocally.
This task is basically a generalization of one-dimensional cellular automata.
See also
Cellular automata (natureofcode.com)
| #C.23 | C# |
using System;
using System.Collections;
namespace ElementaryCellularAutomaton
{
class Automata
{
BitArray cells, ncells;
const int MAX_CELLS = 19;
public void run()
{
cells = new BitArray(MAX_CELLS);
ncells = new BitArray(MAX_CELLS);
while (true)
{
Console.Clear();
Console.WriteLine("What Rule do you want to visualize");
doRule(int.Parse(Console.ReadLine()));
Console.WriteLine("Press any key to continue...");
Console.ReadKey();
}
}
private byte getCells(int index)
{
byte b;
int i1 = index - 1,
i2 = index,
i3 = index + 1;
if (i1 < 0) i1 = MAX_CELLS - 1;
if (i3 >= MAX_CELLS) i3 -= MAX_CELLS;
b = Convert.ToByte(
4 * Convert.ToByte(cells.Get(i1)) +
2 * Convert.ToByte(cells.Get(i2)) +
Convert.ToByte(cells.Get(i3)));
return b;
}
private string getBase2(int i)
{
string s = Convert.ToString(i, 2);
while (s.Length < 8)
{ s = "0" + s; }
return s;
}
private void doRule(int rule)
{
Console.Clear();
string rl = getBase2(rule);
cells.SetAll(false);
ncells.SetAll(false);
cells.Set(MAX_CELLS / 2, true);
Console.WriteLine("Rule: " + rule + "\n----------\n");
for (int gen = 0; gen < 51; gen++)
{
Console.Write("{0, 4}", gen + ": ");
foreach (bool b in cells)
Console.Write(b ? "#" : ".");
Console.WriteLine("");
int i = 0;
while (true)
{
byte b = getCells(i);
ncells[i] = '1' == rl[7 - b] ? true : false;
if (++i == MAX_CELLS) break;
}
i = 0;
foreach (bool b in ncells)
cells[i++] = b;
}
Console.WriteLine("");
}
};
class Program
{
static void Main(string[] args)
{
Automata t = new Automata();
t.run();
}
}
}
|
http://rosettacode.org/wiki/Factorial | Factorial | Definitions
The factorial of 0 (zero) is defined as being 1 (unity).
The Factorial Function of a positive integer, n, is defined as the product of the sequence:
n, n-1, n-2, ... 1
Task
Write a function to return the factorial of a number.
Solutions can be iterative or recursive.
Support for trapping negative n errors is optional.
Related task
Primorial numbers
| #Stata | Stata | mata
real scalar function fact1(real scalar n) {
if (n<2) return(1)
else return(fact1(n-1)*n)
}
real scalar function fact2(real scalar n) {
a=1
for (i=2;i<=n;i++) a=a*i
return(a)
}
printf("%f\n",fact1(8))
printf("%f\n",fact2(8))
printf("%f\n",factorial(8)) |
http://rosettacode.org/wiki/Even_or_odd | Even or odd | Task
Test whether an integer is even or odd.
There is more than one way to solve this task:
Use the even and odd predicates, if the language provides them.
Check the least significant digit. With binary integers, i bitwise-and 1 equals 0 iff i is even, or equals 1 iff i is odd.
Divide i by 2. The remainder equals 0 iff i is even. The remainder equals +1 or -1 iff i is odd.
Use modular congruences:
i ≡ 0 (mod 2) iff i is even.
i ≡ 1 (mod 2) iff i is odd.
| #Stata | Stata | mata
function iseven(n) {
return(mod(n,2)==0)
}
function isodd(n) {
return(mod(n,2)==1)
}
end |
http://rosettacode.org/wiki/Even_or_odd | Even or odd | Task
Test whether an integer is even or odd.
There is more than one way to solve this task:
Use the even and odd predicates, if the language provides them.
Check the least significant digit. With binary integers, i bitwise-and 1 equals 0 iff i is even, or equals 1 iff i is odd.
Divide i by 2. The remainder equals 0 iff i is even. The remainder equals +1 or -1 iff i is odd.
Use modular congruences:
i ≡ 0 (mod 2) iff i is even.
i ≡ 1 (mod 2) iff i is odd.
| #Swift | Swift | func isEven(n:Int) -> Bool {
// Bitwise check
if (n & 1 != 0) {
return false
}
// Mod check
if (n % 2 != 0) {
return false
}
return true
} |
http://rosettacode.org/wiki/Echo_server | Echo server | Create a network service that sits on TCP port 12321, which accepts connections on that port, and which echoes complete lines (using a carriage-return/line-feed sequence as line separator) back to clients. No error handling is required. For the purposes of testing, it is only necessary to support connections from localhost (127.0.0.1 or perhaps ::1). Logging of connection information to standard output is recommended.
The implementation must be able to handle simultaneous connections from multiple clients. A multi-threaded or multi-process solution may be used. Each connection must be able to echo more than a single line.
The implementation must not stop responding to other clients if one client sends a partial line or stops reading responses.
| #Delphi | Delphi | program EchoServer;
{$APPTYPE CONSOLE}
uses SysUtils, IdContext, IdTCPServer;
type
TEchoServer = class
private
FTCPServer: TIdTCPServer;
public
constructor Create;
destructor Destroy; override;
procedure TCPServerExecute(AContext: TIdContext);
end;
constructor TEchoServer.Create;
begin
FTCPServer := TIdTCPServer.Create(nil);
FTCPServer.DefaultPort := 12321;
FTCPServer.OnExecute := TCPServerExecute;
FTCPServer.Active := True;
end;
destructor TEchoServer.Destroy;
begin
FTCPServer.Active := False;
FTCPServer.Free;
inherited Destroy;
end;
procedure TEchoServer.TCPServerExecute(AContext: TIdContext);
var
lCmdLine: string;
begin
lCmdLine := AContext.Connection.IOHandler.ReadLn;
Writeln('>' + lCmdLine);
AContext.Connection.IOHandler.Writeln('>' + lCmdLine);
if SameText(lCmdLine, 'QUIT') then
begin
AContext.Connection.IOHandler.Writeln('Disconnecting');
AContext.Connection.Disconnect;
end;
end;
var
lEchoServer: TEchoServer;
begin
lEchoServer := TEchoServer.Create;
try
Writeln('Delphi Echo Server');
Writeln('Press Enter to quit');
Readln;
finally
lEchoServer.Free;
end;
end. |
http://rosettacode.org/wiki/Elementary_cellular_automaton/Infinite_length | Elementary cellular automaton/Infinite length | The purpose of this task is to create a version of an Elementary cellular automaton whose number of cells is only limited by the memory size of the computer.
To be precise, consider the state of the automaton to be made of an infinite number of cells, but with a bounded support. In other words, to describe the state of the automaton, you need a finite number of adjacent cells, along with their individual state, and you then consider that the individual state of each of all other cells is the negation of the closest individual cell among the previously defined finite number of cells.
Examples:
1 -> ..., 0, 0, 1, 0, 0, ...
0, 1 -> ..., 1, 1, 0, 1, 0, 0, ...
1, 0, 1 -> ..., 0, 0, 1, 0, 1, 0, 0, ...
More complex methods can be imagined, provided it is possible to somehow encode the infinite sections. But for this task we will stick to this simple version.
| #Raku | Raku | class Automaton {
has $.rule;
has @.cells;
has @.code = $!rule.fmt('%08b').flip.comb».Int;
method gist { @!cells.map({+$_ ?? '▲' !! '░'}).join }
method succ {
self.new: :$!rule, :@!code, :cells(
' ',
|@!code[
4 «*« @!cells.rotate(-1)
»+« 2 «*« @!cells
»+« @!cells.rotate(1)
],
' '
)
}
}
my Automaton $a .= new: :rule(90), :cells(flat '010'.comb);
# display the first 20 rows
say $a++ for ^20;
# then calculate the other infinite number of rows, (may take a while)
$a++ for ^Inf; |
http://rosettacode.org/wiki/Elementary_cellular_automaton/Infinite_length | Elementary cellular automaton/Infinite length | The purpose of this task is to create a version of an Elementary cellular automaton whose number of cells is only limited by the memory size of the computer.
To be precise, consider the state of the automaton to be made of an infinite number of cells, but with a bounded support. In other words, to describe the state of the automaton, you need a finite number of adjacent cells, along with their individual state, and you then consider that the individual state of each of all other cells is the negation of the closest individual cell among the previously defined finite number of cells.
Examples:
1 -> ..., 0, 0, 1, 0, 0, ...
0, 1 -> ..., 1, 1, 0, 1, 0, 0, ...
1, 0, 1 -> ..., 0, 0, 1, 0, 1, 0, 0, ...
More complex methods can be imagined, provided it is possible to somehow encode the infinite sections. But for this task we will stick to this simple version.
| #Ruby | Ruby | def notcell(c)
c.tr('01','10')
end
def eca_infinite(cells, rule)
neighbours2next = Hash[8.times.map{|i|["%03b"%i, "01"[rule[i]]]}]
c = cells
Enumerator.new do |y|
loop do
y << c
c = notcell(c[0])*2 + c + notcell(c[-1])*2 # Extend and pad the ends
c = (1..c.size-2).map{|i| neighbours2next[c[i-1..i+1]]}.join
end
end
end
if __FILE__ == $0
lines = 25
for rule in [90, 30]
puts "\nRule: %i" % rule
for i, c in (0...lines).zip(eca_infinite('1', rule))
puts '%2i: %s%s' % [i, ' '*(lines - i), c.tr('01', '.#')]
end
end
end |
http://rosettacode.org/wiki/EKG_sequence_convergence | EKG sequence convergence | The sequence is from the natural numbers and is defined by:
a(1) = 1;
a(2) = Start = 2;
for n > 2, a(n) shares at least one prime factor with a(n-1) and is the smallest such natural number not already used.
The sequence is called the EKG sequence (after its visual similarity to an electrocardiogram when graphed).
Variants of the sequence can be generated starting 1, N where N is any natural number larger than one. For the purposes of this task let us call:
The sequence described above , starting 1, 2, ... the EKG(2) sequence;
the sequence starting 1, 3, ... the EKG(3) sequence;
... the sequence starting 1, N, ... the EKG(N) sequence.
Convergence
If an algorithm that keeps track of the minimum amount of numbers and their corresponding prime factors used to generate the next term is used, then this may be known as the generators essential state. Two EKG generators with differing starts can converge to produce the same sequence after initial differences.
EKG(N1) and EKG(N2) are said to to have converged at and after generation a(c) if state_of(EKG(N1).a(c)) == state_of(EKG(N2).a(c)).
Task
Calculate and show here the first 10 members of EKG(2).
Calculate and show here the first 10 members of EKG(5).
Calculate and show here the first 10 members of EKG(7).
Calculate and show here the first 10 members of EKG(9).
Calculate and show here the first 10 members of EKG(10).
Calculate and show here at which term EKG(5) and EKG(7) converge (stretch goal).
Related Tasks
Greatest common divisor
Sieve of Eratosthenes
Reference
The EKG Sequence and the Tree of Numbers. (Video).
| #.7B.7Bheader.7CVlang.7D | {{header|Vlang} | fn gcd(aa int, bb int) int {
mut a,mut b:=aa,bb
for a != b {
if a > b {
a -= b
} else {
b -= a
}
}
return a
}
fn are_same(ss []int, tt []int) bool {
mut s,mut t:=ss.clone(),tt.clone()
le := s.len
if le != t.len {
return false
}
s.sort()
t.sort()
for i in 0..le {
if s[i] != t[i] {
return false
}
}
return true
}
const limit = 100
fn main() {
starts := [2, 5, 7, 9, 10]
mut ekg := [5][limit]int{}
for s, start in starts {
ekg[s][0] = 1
ekg[s][1] = start
for n in 2..limit {
for i := 2; ; i++ {
// a potential sequence member cannot already have been used
// and must have a factor in common with previous member
if !ekg[s][..n].contains(i) && gcd(ekg[s][n-1], i) > 1 {
ekg[s][n] = i
break
}
}
}
println("EKG(${start:2}): ${ekg[s][..30]}")
}
// now compare EKG5 and EKG7 for convergence
for i in 2..limit {
if ekg[1][i] == ekg[2][i] && are_same(ekg[1][..i], ekg[2][..i]) {
println("\nEKG(5) and EKG(7) converge at term ${i+1}")
return
}
}
println("\nEKG5(5) and EKG(7) do not converge within $limit terms")
} |
http://rosettacode.org/wiki/EKG_sequence_convergence | EKG sequence convergence | The sequence is from the natural numbers and is defined by:
a(1) = 1;
a(2) = Start = 2;
for n > 2, a(n) shares at least one prime factor with a(n-1) and is the smallest such natural number not already used.
The sequence is called the EKG sequence (after its visual similarity to an electrocardiogram when graphed).
Variants of the sequence can be generated starting 1, N where N is any natural number larger than one. For the purposes of this task let us call:
The sequence described above , starting 1, 2, ... the EKG(2) sequence;
the sequence starting 1, 3, ... the EKG(3) sequence;
... the sequence starting 1, N, ... the EKG(N) sequence.
Convergence
If an algorithm that keeps track of the minimum amount of numbers and their corresponding prime factors used to generate the next term is used, then this may be known as the generators essential state. Two EKG generators with differing starts can converge to produce the same sequence after initial differences.
EKG(N1) and EKG(N2) are said to to have converged at and after generation a(c) if state_of(EKG(N1).a(c)) == state_of(EKG(N2).a(c)).
Task
Calculate and show here the first 10 members of EKG(2).
Calculate and show here the first 10 members of EKG(5).
Calculate and show here the first 10 members of EKG(7).
Calculate and show here the first 10 members of EKG(9).
Calculate and show here the first 10 members of EKG(10).
Calculate and show here at which term EKG(5) and EKG(7) converge (stretch goal).
Related Tasks
Greatest common divisor
Sieve of Eratosthenes
Reference
The EKG Sequence and the Tree of Numbers. (Video).
| #Wren | Wren | import "/sort" for Sort
import "/math" for Int
import "/fmt" for Fmt
var areSame = Fn.new { |s, t|
var le = s.count
if (le != t.count) return false
Sort.quick(s)
Sort.quick(t)
for (i in 0...le) if (s[i] != t[i]) return false
return true
}
var limit = 100
var starts = [2, 5, 7, 9, 10]
var ekg = List.filled(5, null)
for (i in 0..4) ekg[i] = List.filled(limit, 0)
var s = 0
for (start in starts) {
ekg[s][0] = 1
ekg[s][1] = start
for (n in 2...limit) {
var i = 2
while (true) {
// a potential sequence member cannot already have been used
// and must have a factor in common with previous member
if (!ekg[s].take(n).contains(i) && Int.gcd(ekg[s][n-1], i) > 1) {
ekg[s][n] = i
break
}
i = i + 1
}
}
Fmt.print("EKG($2d): $2d", start, ekg[s].take(30).toList)
s = s + 1
}
// now compare EKG5 and EKG7 for convergence
for (i in 2...limit) {
if (ekg[1][i] == ekg[2][i] && areSame.call(ekg[1][0...i], ekg[2][0...i])) {
System.print("\nEKG(5) and EKG(7) converge at term %(i+1).")
return
}
}
System.print("\nEKG5(5) and EKG(7) do not converge within %(limit) terms.") |
http://rosettacode.org/wiki/Empty_string | Empty string | Languages may have features for dealing specifically with empty strings
(those containing no characters).
Task
Demonstrate how to assign an empty string to a variable.
Demonstrate how to check that a string is empty.
Demonstrate how to check that a string is not empty.
Other tasks related to string operations:
Metrics
Array length
String length
Copy a string
Empty string (assignment)
Counting
Word frequency
Letter frequency
Jewels and stones
I before E except after C
Bioinformatics/base count
Count occurrences of a substring
Count how many vowels and consonants occur in a string
Remove/replace
XXXX redacted
Conjugate a Latin verb
Remove vowels from a string
String interpolation (included)
Strip block comments
Strip comments from a string
Strip a set of characters from a string
Strip whitespace from a string -- top and tail
Strip control codes and extended characters from a string
Anagrams/Derangements/shuffling
Word wheel
ABC problem
Sattolo cycle
Knuth shuffle
Ordered words
Superpermutation minimisation
Textonyms (using a phone text pad)
Anagrams
Anagrams/Deranged anagrams
Permutations/Derangements
Find/Search/Determine
ABC words
Odd words
Word ladder
Semordnilap
Word search
Wordiff (game)
String matching
Tea cup rim text
Alternade words
Changeable words
State name puzzle
String comparison
Unique characters
Unique characters in each string
Extract file extension
Levenshtein distance
Palindrome detection
Common list elements
Longest common suffix
Longest common prefix
Compare a list of strings
Longest common substring
Find common directory path
Words from neighbour ones
Change e letters to i in words
Non-continuous subsequences
Longest common subsequence
Longest palindromic substrings
Longest increasing subsequence
Words containing "the" substring
Sum of the digits of n is substring of n
Determine if a string is numeric
Determine if a string is collapsible
Determine if a string is squeezable
Determine if a string has all unique characters
Determine if a string has all the same characters
Longest substrings without repeating characters
Find words which contains all the vowels
Find words which contains most consonants
Find words which contains more than 3 vowels
Find words which first and last three letters are equals
Find words which odd letters are consonants and even letters are vowels or vice_versa
Formatting
Substring
Rep-string
Word wrap
String case
Align columns
Literals/String
Repeat a string
Brace expansion
Brace expansion using ranges
Reverse a string
Phrase reversals
Comma quibbling
Special characters
String concatenation
Substring/Top and tail
Commatizing numbers
Reverse words in a string
Suffixation of decimal numbers
Long literals, with continuations
Numerical and alphabetical suffixes
Abbreviations, easy
Abbreviations, simple
Abbreviations, automatic
Song lyrics/poems/Mad Libs/phrases
Mad Libs
Magic 8-ball
99 Bottles of Beer
The Name Game (a song)
The Old lady swallowed a fly
The Twelve Days of Christmas
Tokenize
Text between
Tokenize a string
Word break problem
Tokenize a string with escaping
Split a character string based on change of character
Sequences
Show ASCII table
De Bruijn sequences
Self-referential sequences
Generate lower case ASCII alphabet
| #VBScript | VBScript | Dim s As String
' Assign empty string:
s = ""
' or
s = String.Empty
' Check for empty string only (false if s is null):
If s IsNot Nothing AndAlso s.Length = 0 Then
End If
' Check for null or empty (more idiomatic in .NET):
If String.IsNullOrEmpty(s) Then
End If |
http://rosettacode.org/wiki/Empty_string | Empty string | Languages may have features for dealing specifically with empty strings
(those containing no characters).
Task
Demonstrate how to assign an empty string to a variable.
Demonstrate how to check that a string is empty.
Demonstrate how to check that a string is not empty.
Other tasks related to string operations:
Metrics
Array length
String length
Copy a string
Empty string (assignment)
Counting
Word frequency
Letter frequency
Jewels and stones
I before E except after C
Bioinformatics/base count
Count occurrences of a substring
Count how many vowels and consonants occur in a string
Remove/replace
XXXX redacted
Conjugate a Latin verb
Remove vowels from a string
String interpolation (included)
Strip block comments
Strip comments from a string
Strip a set of characters from a string
Strip whitespace from a string -- top and tail
Strip control codes and extended characters from a string
Anagrams/Derangements/shuffling
Word wheel
ABC problem
Sattolo cycle
Knuth shuffle
Ordered words
Superpermutation minimisation
Textonyms (using a phone text pad)
Anagrams
Anagrams/Deranged anagrams
Permutations/Derangements
Find/Search/Determine
ABC words
Odd words
Word ladder
Semordnilap
Word search
Wordiff (game)
String matching
Tea cup rim text
Alternade words
Changeable words
State name puzzle
String comparison
Unique characters
Unique characters in each string
Extract file extension
Levenshtein distance
Palindrome detection
Common list elements
Longest common suffix
Longest common prefix
Compare a list of strings
Longest common substring
Find common directory path
Words from neighbour ones
Change e letters to i in words
Non-continuous subsequences
Longest common subsequence
Longest palindromic substrings
Longest increasing subsequence
Words containing "the" substring
Sum of the digits of n is substring of n
Determine if a string is numeric
Determine if a string is collapsible
Determine if a string is squeezable
Determine if a string has all unique characters
Determine if a string has all the same characters
Longest substrings without repeating characters
Find words which contains all the vowels
Find words which contains most consonants
Find words which contains more than 3 vowels
Find words which first and last three letters are equals
Find words which odd letters are consonants and even letters are vowels or vice_versa
Formatting
Substring
Rep-string
Word wrap
String case
Align columns
Literals/String
Repeat a string
Brace expansion
Brace expansion using ranges
Reverse a string
Phrase reversals
Comma quibbling
Special characters
String concatenation
Substring/Top and tail
Commatizing numbers
Reverse words in a string
Suffixation of decimal numbers
Long literals, with continuations
Numerical and alphabetical suffixes
Abbreviations, easy
Abbreviations, simple
Abbreviations, automatic
Song lyrics/poems/Mad Libs/phrases
Mad Libs
Magic 8-ball
99 Bottles of Beer
The Name Game (a song)
The Old lady swallowed a fly
The Twelve Days of Christmas
Tokenize
Text between
Tokenize a string
Word break problem
Tokenize a string with escaping
Split a character string based on change of character
Sequences
Show ASCII table
De Bruijn sequences
Self-referential sequences
Generate lower case ASCII alphabet
| #Visual_Basic | Visual Basic | Dim s As String
' Assign empty string:
s = ""
' or
s = String.Empty
' Check for empty string only (false if s is null):
If s IsNot Nothing AndAlso s.Length = 0 Then
End If
' Check for null or empty (more idiomatic in .NET):
If String.IsNullOrEmpty(s) Then
End If |
http://rosettacode.org/wiki/Empty_program | Empty program | Task
Create the simplest possible program that is still considered "correct."
| #Run_BASIC | Run BASIC | end ' actually a blank is ok |
http://rosettacode.org/wiki/Empty_program | Empty program | Task
Create the simplest possible program that is still considered "correct."
| #Rust | Rust | fn main(){} |
http://rosettacode.org/wiki/Empty_program | Empty program | Task
Create the simplest possible program that is still considered "correct."
| #Scala | Scala | object emptyProgram extends App {} |
http://rosettacode.org/wiki/Earliest_difference_between_prime_gaps | Earliest difference between prime gaps | When calculating prime numbers > 2, the difference between adjacent primes is always an even number. This difference, also referred to as the gap, varies in an random pattern; at least, no pattern has ever been discovered, and it is strongly conjectured that no pattern exists. However, it is also conjectured that between some two adjacent primes will be a gap corresponding to every positive even integer.
gap
minimal
starting
prime
ending
prime
2
3
5
4
7
11
6
23
29
8
89
97
10
139
149
12
199
211
14
113
127
16
1831
1847
18
523
541
20
887
907
22
1129
1151
24
1669
1693
26
2477
2503
28
2971
2999
30
4297
4327
This task involves locating the minimal primes corresponding to those gaps.
Though every gap value exists, they don't seem to come in any particular order. For example, this table shows the gaps and minimum starting value primes for 2 through 30:
For the purposes of this task, considering only primes greater than 2, consider prime gaps that differ by exactly two to be adjacent.
Task
For each order of magnitude m from 10¹ through 10⁶:
Find the first two sets of adjacent minimum prime gaps where the absolute value of the difference between the prime gap start values is greater than m.
E.G.
For an m of 10¹;
The start value of gap 2 is 3, the start value of gap 4 is 7, the difference is 7 - 3 or 4. 4 < 10¹ so keep going.
The start value of gap 4 is 7, the start value of gap 6 is 23, the difference is 23 - 7, or 16. 16 > 10¹ so this the earliest adjacent gap difference > 10¹.
Stretch goal
Do the same for 10⁷ and 10⁸ (and higher?) orders of magnitude
Note: the earliest value found for each order of magnitude may not be unique, in fact, is not unique; also, with the gaps in ascending order, the minimal starting values are not strictly ascending.
| #C.2B.2B | C++ | #include <iostream>
#include <locale>
#include <unordered_map>
#include <primesieve.hpp>
class prime_gaps {
public:
prime_gaps() { last_prime_ = iterator_.next_prime(); }
uint64_t find_gap_start(uint64_t gap);
private:
primesieve::iterator iterator_;
uint64_t last_prime_;
std::unordered_map<uint64_t, uint64_t> gap_starts_;
};
uint64_t prime_gaps::find_gap_start(uint64_t gap) {
auto i = gap_starts_.find(gap);
if (i != gap_starts_.end())
return i->second;
for (;;) {
uint64_t prev = last_prime_;
last_prime_ = iterator_.next_prime();
uint64_t diff = last_prime_ - prev;
gap_starts_.emplace(diff, prev);
if (gap == diff)
return prev;
}
}
int main() {
std::cout.imbue(std::locale(""));
const uint64_t limit = 100000000000;
prime_gaps pg;
for (uint64_t pm = 10, gap1 = 2;;) {
uint64_t start1 = pg.find_gap_start(gap1);
uint64_t gap2 = gap1 + 2;
uint64_t start2 = pg.find_gap_start(gap2);
uint64_t diff = start2 > start1 ? start2 - start1 : start1 - start2;
if (diff > pm) {
std::cout << "Earliest difference > " << pm
<< " between adjacent prime gap starting primes:\n"
<< "Gap " << gap1 << " starts at " << start1 << ", gap "
<< gap2 << " starts at " << start2 << ", difference is "
<< diff << ".\n\n";
if (pm == limit)
break;
pm *= 10;
} else {
gap1 = gap2;
}
}
} |
http://rosettacode.org/wiki/Element-wise_operations | Element-wise operations | This task is similar to:
Matrix multiplication
Matrix transposition
Task
Implement basic element-wise matrix-matrix and scalar-matrix operations, which can be referred to in other, higher-order tasks.
Implement:
addition
subtraction
multiplication
division
exponentiation
Extend the task if necessary to include additional basic operations, which should not require their own specialised task.
| #AutoHotkey | AutoHotkey | ElementWise(M, operation, Val){
A := Obj_Copy(M),
for r, obj in A
for c, v in obj {
V := IsObject(Val) ? Val[r, c] : Val
switch, operation {
case "+": A[r, c] := A[r, c] + V
case "-": A[r, c] := A[r, c] - V
case "*": A[r, c] := A[r, c] * V
case "/": A[r, c] := A[r, c] / V
case "Mod": A[r, c] := Mod(A[r, c], V)
case "^": A[r, c] := A[r, c] ** V
}
}
return A
} |
http://rosettacode.org/wiki/Egyptian_division | Egyptian division | Egyptian division is a method of dividing integers using addition and
doubling that is similar to the algorithm of Ethiopian multiplication
Algorithm:
Given two numbers where the dividend is to be divided by the divisor:
Start the construction of a table of two columns: powers_of_2, and doublings; by a first row of a 1 (i.e. 2^0) in the first column and 1 times the divisor in the first row second column.
Create the second row with columns of 2 (i.e 2^1), and 2 * divisor in order.
Continue with successive i’th rows of 2^i and 2^i * divisor.
Stop adding rows, and keep only those rows, where 2^i * divisor is less than or equal to the dividend.
We now assemble two separate sums that both start as zero, called here answer and accumulator
Consider each row of the table, in the reverse order of its construction.
If the current value of the accumulator added to the doublings cell would be less than or equal to the dividend then add it to the accumulator, as well as adding the powers_of_2 cell value to the answer.
When the first row has been considered as above, then the integer division of dividend by divisor is given by answer.
(And the remainder is given by the absolute value of accumulator - dividend).
Example: 580 / 34
Table creation:
powers_of_2
doublings
1
34
2
68
4
136
8
272
16
544
Initialization of sums:
powers_of_2
doublings
answer
accumulator
1
34
2
68
4
136
8
272
16
544
0
0
Considering table rows, bottom-up:
When a row is considered it is shown crossed out if it is not accumulated, or bold if the row causes summations.
powers_of_2
doublings
answer
accumulator
1
34
2
68
4
136
8
272
16
544
16
544
powers_of_2
doublings
answer
accumulator
1
34
2
68
4
136
8
272
16
544
16
544
powers_of_2
doublings
answer
accumulator
1
34
2
68
4
136
16
544
8
272
16
544
powers_of_2
doublings
answer
accumulator
1
34
2
68
16
544
4
136
8
272
16
544
powers_of_2
doublings
answer
accumulator
1
34
17
578
2
68
4
136
8
272
16
544
Answer
So 580 divided by 34 using the Egyptian method is 17 remainder (578 - 580) or 2.
Task
The task is to create a function that does Egyptian division. The function should
closely follow the description above in using a list/array of powers of two, and
another of doublings.
Functions should be clear interpretations of the algorithm.
Use the function to divide 580 by 34 and show the answer here, on this page.
Related tasks
Egyptian fractions
References
Egyptian Number System
| #ALGOL_68 | ALGOL 68 | BEGIN
# performs Egyptian division of dividend by divisor, setting quotient and remainder #
# this uses 32 bit numbers, so a table of 32 powers of 2 should be sufficient #
# ( divisors > 2^30 will probably overflow - this is not checked here ) #
PROC egyptian division = ( INT dividend, divisor, REF INT quotient, remainder )VOID:
BEGIN
[ 1 : 32 ]INT powers of 2, doublings;
# initialise the powers of 2 and doublings tables #
powers of 2[ 1 ] := 1;
doublings [ 1 ] := divisor;
INT table pos := 1;
WHILE table pos +:= 1;
powers of 2[ table pos ] := powers of 2[ table pos - 1 ] * 2;
doublings [ table pos ] := doublings [ table pos - 1 ] * 2;
doublings[ table pos ] <= dividend
DO
SKIP
OD;
# construct the accumulator and answer #
INT accumulator := 0, answer := 0;
WHILE table pos >=1
DO
IF ( accumulator + doublings[ table pos ] ) <= dividend
THEN
accumulator +:= doublings [ table pos ];
answer +:= powers of 2[ table pos ]
FI;
table pos -:= 1
OD;
quotient := answer;
remainder := ABS ( accumulator - dividend )
END # egyptian division # ;
# task test case #
INT quotient, remainder;
egyptian division( 580, 34, quotient, remainder );
print( ( "580 divided by 34 is: ", whole( quotient, 0 ), " remainder: ", whole( remainder, 0 ), newline ) )
END |
http://rosettacode.org/wiki/Eertree | Eertree | An eertree is a data structure designed for efficient processing of certain palindrome tasks, for instance counting the number of sub-palindromes in an input string.
The data structure has commonalities to both tries and suffix trees.
See links below.
Task
Construct an eertree for the string "eertree", then output all sub-palindromes by traversing the tree.
See also
Wikipedia entry: trie.
Wikipedia entry: suffix tree
Cornell University Library, Computer Science, Data Structures and Algorithms ───► EERTREE: An Efficient Data Structure for Processing Palindromes in Strings.
| #Julia | Julia | mutable struct Node
edges::Dict{Char, Node}
link::Union{Node, Missing}
sz::Int
Node() = new(Dict(), missing, 0)
end
sizednode(x) = (n = Node(); n.sz = x; n)
function eertree(str)
nodes = Vector{Node}()
oddroot = sizednode(-1)
evenroot = sizednode(0)
oddroot.link = evenroot
evenroot.link = oddroot
S = "0"
maxsuffix = evenroot
function maxsuffixpal(startnode,a::Char)
# Traverse the suffix-palindromes of tree looking for equality with a
u = startnode
i = length(S)
k = u.sz
while u !== oddroot && S[i - k] != a
if u === u.link
throw("circular reference above oddroot")
end
u = u.link
k = u.sz
end
u
end
function addchar(a::Char)
Q = maxsuffixpal(maxsuffix, a)
creatednode = !haskey(Q.edges, a)
if creatednode
P = sizednode(Q.sz + 2)
push!(nodes, P)
if P.sz == 1
P.link = evenroot
else
P.link = maxsuffixpal(Q.link, a).edges[a]
end
Q.edges[a] = P # adds edge (Q, P)
end
maxsuffix = Q.edges[a] # P becomes the new maxsuffix
S *= string(a)
creatednode
end
function getsubpalindromes()
result = Vector{String}()
getsubpalindromes(oddroot, [oddroot], "", result)
getsubpalindromes(evenroot, [evenroot], "", result)
result
end
function getsubpalindromes(nd, nodestohere, charstohere, result)
for (lnkname, nd2) in nd.edges
getsubpalindromes(nd2, vcat(nodestohere, nd2), charstohere * lnkname, result)
end
if nd !== oddroot && nd !== evenroot
assembled = reverse(charstohere) *
(nodestohere[1] === evenroot ? charstohere : charstohere[2:end])
push!(result, assembled)
end
end
println("Results of processing string \"$str\":")
for c in str
addchar(c)
end
println("Number of sub-palindromes: ", length(nodes))
println("Sub-palindromes: ", getsubpalindromes())
end
eertree("eertree")
|
http://rosettacode.org/wiki/Eertree | Eertree | An eertree is a data structure designed for efficient processing of certain palindrome tasks, for instance counting the number of sub-palindromes in an input string.
The data structure has commonalities to both tries and suffix trees.
See links below.
Task
Construct an eertree for the string "eertree", then output all sub-palindromes by traversing the tree.
See also
Wikipedia entry: trie.
Wikipedia entry: suffix tree
Cornell University Library, Computer Science, Data Structures and Algorithms ───► EERTREE: An Efficient Data Structure for Processing Palindromes in Strings.
| #Kotlin | Kotlin | // version 1.1.4
class Node {
val edges = mutableMapOf<Char, Node>() // edges (or forward links)
var link: Node? = null // suffix link (backward links)
var len = 0 // the length of the node
}
class Eertree(str: String) {
val nodes = mutableListOf<Node>()
private val rto = Node() // odd length root node, or node -1
private val rte = Node() // even length root node, or node 0
private val s = StringBuilder("0") // accumulated input string, T = S[1..i]
private var maxSufT = rte // maximum suffix of tree T
init {
// Initialize and build the tree
rte.link = rto
rto.link = rte
rto.len = -1
rte.len = 0
for (ch in str) add(ch)
}
private fun getMaxSuffixPal(startNode: Node, a: Char): Node {
// We traverse the suffix-palindromes of T in the order of decreasing length.
// For each palindrome we read its length k and compare T[i-k] against a
// until we get an equality or arrive at the -1 node.
var u = startNode
val i = s.length
var k = u.len
while (u !== rto && s[i - k - 1] != a) {
if (u === u.link!!) throw RuntimeException("Infinite loop detected")
u = u.link!!
k = u.len
}
return u
}
private fun add(a: Char): Boolean {
// We need to find the maximum suffix-palindrome P of Ta
// Start by finding maximum suffix-palindrome Q of T.
// To do this, we traverse the suffix-palindromes of T
// in the order of decreasing length, starting with maxSuf(T)
val q = getMaxSuffixPal(maxSufT, a)
// We check Q to see whether it has an outgoing edge labeled by a.
val createANewNode = a !in q.edges.keys
if (createANewNode) {
// We create the node P of length Q + 2
val p = Node()
nodes.add(p)
p.len = q.len + 2
if (p.len == 1) {
// if P = a, create the suffix link (P, 0)
p.link = rte
}
else {
// It remains to create the suffix link from P if |P|>1. Just
// continue traversing suffix-palindromes of T starting with the
// the suffix link of Q.
p.link = getMaxSuffixPal(q.link!!, a).edges[a]
}
// create the edge (Q, P)
q.edges[a] = p
}
// P becomes the new maxSufT
maxSufT = q.edges[a]!!
// Store accumulated input string
s.append(a)
return createANewNode
}
fun getSubPalindromes(): List<String> {
// Traverse tree to find sub-palindromes
val result = mutableListOf<String>()
// Odd length words
getSubPalindromes(rto, listOf(rto), "", result)
// Even length words
getSubPalindromes(rte, listOf(rte), "", result)
return result
}
private fun getSubPalindromes(nd: Node, nodesToHere: List<Node>,
charsToHere: String, result: MutableList<String>) {
// Each node represents a palindrome, which can be reconstructed
// by the path from the root node to each non-root node.
// Traverse all edges, since they represent other palindromes
for ((lnkName, nd2) in nd.edges) {
getSubPalindromes(nd2, nodesToHere + nd2, charsToHere + lnkName, result)
}
// Reconstruct based on charsToHere characters.
if (nd !== rto && nd !== rte) { // Don't print for root nodes
val assembled = charsToHere.reversed() +
if (nodesToHere[0] === rte) // Even string
charsToHere
else // Odd string
charsToHere.drop(1)
result.add(assembled)
}
}
}
fun main(args: Array<String>) {
val str = "eertree"
println("Processing string '$str'")
val eertree = Eertree(str)
println("Number of sub-palindromes: ${eertree.nodes.size}")
val result = eertree.getSubPalindromes()
println("Sub-palindromes: $result")
} |
http://rosettacode.org/wiki/Ethiopian_multiplication | Ethiopian multiplication | Ethiopian multiplication is a method of multiplying integers using only addition, doubling, and halving.
Method:
Take two numbers to be multiplied and write them down at the top of two columns.
In the left-hand column repeatedly halve the last number, discarding any remainders, and write the result below the last in the same column, until you write a value of 1.
In the right-hand column repeatedly double the last number and write the result below. stop when you add a result in the same row as where the left hand column shows 1.
Examine the table produced and discard any row where the value in the left column is even.
Sum the values in the right-hand column that remain to produce the result of multiplying the original two numbers together
For example: 17 × 34
17 34
Halving the first column:
17 34
8
4
2
1
Doubling the second column:
17 34
8 68
4 136
2 272
1 544
Strike-out rows whose first cell is even:
17 34
8 68
4 136
2 272
1 544
Sum the remaining numbers in the right-hand column:
17 34
8 --
4 ---
2 ---
1 544
====
578
So 17 multiplied by 34, by the Ethiopian method is 578.
Task
The task is to define three named functions/methods/procedures/subroutines:
one to halve an integer,
one to double an integer, and
one to state if an integer is even.
Use these functions to create a function that does Ethiopian multiplication.
References
Ethiopian multiplication explained (BBC Video clip)
A Night Of Numbers - Go Forth And Multiply (Video)
Russian Peasant Multiplication
Programming Praxis: Russian Peasant Multiplication
| #PowerShell | PowerShell | function isEven {
param ([int]$value)
return [bool]($value % 2 -eq 0)
}
function doubleValue {
param ([int]$value)
return [int]($value * 2)
}
function halveValue {
param ([int]$value)
return [int]($value / 2)
}
function multiplyValues {
param (
[int]$plier,
[int]$plicand,
[int]$temp = 0
)
while ($plier -ge 1)
{
if (!(isEven $plier)) {
$temp += $plicand
}
$plier = halveValue $plier
$plicand = doubleValue $plicand
}
return $temp
}
multiplyValues 17 34 |
http://rosettacode.org/wiki/Elementary_cellular_automaton | Elementary cellular automaton | An elementary cellular automaton is a one-dimensional cellular automaton where there are two possible states (labeled 0 and 1) and the rule to determine the state of a cell in the next generation depends only on the current state of the cell and its two immediate neighbors. Those three values can be encoded with three bits.
The rules of evolution are then encoded with eight bits indicating the outcome of each of the eight possibilities 111, 110, 101, 100, 011, 010, 001 and 000 in this order. Thus for instance the rule 13 means that a state is updated to 1 only in the cases 011, 010 and 000, since 13 in binary is 0b00001101.
Task
Create a subroutine, program or function that allows to create and visualize the evolution of any of the 256 possible elementary cellular automaton of arbitrary space length and for any given initial state. You can demonstrate your solution with any automaton of your choice.
The space state should wrap: this means that the left-most cell should be considered as the right neighbor of the right-most cell, and reciprocally.
This task is basically a generalization of one-dimensional cellular automata.
See also
Cellular automata (natureofcode.com)
| #C.2B.2B | C++ | #include <bitset>
#include <stdio.h>
#define SIZE 80
#define RULE 30
#define RULE_TEST(x) (RULE & 1 << (7 & (x)))
void evolve(std::bitset<SIZE> &s) {
int i;
std::bitset<SIZE> t(0);
t[SIZE-1] = RULE_TEST( s[0] << 2 | s[SIZE-1] << 1 | s[SIZE-2] );
t[ 0] = RULE_TEST( s[1] << 2 | s[ 0] << 1 | s[SIZE-1] );
for (i = 1; i < SIZE-1; i++)
t[i] = RULE_TEST( s[i+1] << 2 | s[i] << 1 | s[i-1] );
for (i = 0; i < SIZE; i++) s[i] = t[i];
}
void show(std::bitset<SIZE> s) {
int i;
for (i = SIZE; --i; ) printf("%c", s[i] ? '#' : ' ');
printf("\n");
}
int main() {
int i;
std::bitset<SIZE> state(1);
state <<= SIZE / 2;
for (i=0; i<10; i++) {
show(state);
evolve(state);
}
return 0;
} |
http://rosettacode.org/wiki/Factorial | Factorial | Definitions
The factorial of 0 (zero) is defined as being 1 (unity).
The Factorial Function of a positive integer, n, is defined as the product of the sequence:
n, n-1, n-2, ... 1
Task
Write a function to return the factorial of a number.
Solutions can be iterative or recursive.
Support for trapping negative n errors is optional.
Related task
Primorial numbers
| #Swift | Swift | func factorial(_ n: Int) -> Int {
return n < 2 ? 1 : (2...n).reduce(1, *)
} |
http://rosettacode.org/wiki/Even_or_odd | Even or odd | Task
Test whether an integer is even or odd.
There is more than one way to solve this task:
Use the even and odd predicates, if the language provides them.
Check the least significant digit. With binary integers, i bitwise-and 1 equals 0 iff i is even, or equals 1 iff i is odd.
Divide i by 2. The remainder equals 0 iff i is even. The remainder equals +1 or -1 iff i is odd.
Use modular congruences:
i ≡ 0 (mod 2) iff i is even.
i ≡ 1 (mod 2) iff i is odd.
| #Symsyn | Symsyn |
n : 23
if n bit 0
'n is odd' []
else
'n is even' []
|
http://rosettacode.org/wiki/Even_or_odd | Even or odd | Task
Test whether an integer is even or odd.
There is more than one way to solve this task:
Use the even and odd predicates, if the language provides them.
Check the least significant digit. With binary integers, i bitwise-and 1 equals 0 iff i is even, or equals 1 iff i is odd.
Divide i by 2. The remainder equals 0 iff i is even. The remainder equals +1 or -1 iff i is odd.
Use modular congruences:
i ≡ 0 (mod 2) iff i is even.
i ≡ 1 (mod 2) iff i is odd.
| #Tcl | Tcl | package require Tcl 8.5
# Bitwise test is the most efficient
proc tcl::mathfunc::isOdd x { expr {$x & 1} }
proc tcl::mathfunc::isEven x { expr {!($x & 1)} }
puts " # O E"
puts 24:[expr isOdd(24)],[expr isEven(24)]
puts 49:[expr isOdd(49)],[expr isEven(49)] |
http://rosettacode.org/wiki/Echo_server | Echo server | Create a network service that sits on TCP port 12321, which accepts connections on that port, and which echoes complete lines (using a carriage-return/line-feed sequence as line separator) back to clients. No error handling is required. For the purposes of testing, it is only necessary to support connections from localhost (127.0.0.1 or perhaps ::1). Logging of connection information to standard output is recommended.
The implementation must be able to handle simultaneous connections from multiple clients. A multi-threaded or multi-process solution may be used. Each connection must be able to echo more than a single line.
The implementation must not stop responding to other clients if one client sends a partial line or stops reading responses.
| #Erlang | Erlang | -module(echo).
-export([start/0]).
start() ->
spawn(fun () -> {ok, Sock} = gen_tcp:listen(12321, [{packet, line}]),
echo_loop(Sock)
end).
echo_loop(Sock) ->
{ok, Conn} = gen_tcp:accept(Sock),
io:format("Got connection: ~p~n", [Conn]),
Handler = spawn(fun () -> handle(Conn) end),
gen_tcp:controlling_process(Conn, Handler),
echo_loop(Sock).
handle(Conn) ->
receive
{tcp, Conn, Data} ->
gen_tcp:send(Conn, Data),
handle(Conn);
{tcp_closed, Conn} ->
io:format("Connection closed: ~p~n", [Conn])
end. |
http://rosettacode.org/wiki/Elementary_cellular_automaton/Infinite_length | Elementary cellular automaton/Infinite length | The purpose of this task is to create a version of an Elementary cellular automaton whose number of cells is only limited by the memory size of the computer.
To be precise, consider the state of the automaton to be made of an infinite number of cells, but with a bounded support. In other words, to describe the state of the automaton, you need a finite number of adjacent cells, along with their individual state, and you then consider that the individual state of each of all other cells is the negation of the closest individual cell among the previously defined finite number of cells.
Examples:
1 -> ..., 0, 0, 1, 0, 0, ...
0, 1 -> ..., 1, 1, 0, 1, 0, 0, ...
1, 0, 1 -> ..., 0, 0, 1, 0, 1, 0, 0, ...
More complex methods can be imagined, provided it is possible to somehow encode the infinite sections. But for this task we will stick to this simple version.
| #Sidef | Sidef | func evolve(rule, bin) {
var offset = 0
var (l='', r='')
Inf.times {
bin.sub!(/^((.)\g2*)/, {|_s1, s2| l = s2; offset -= s2.len; s2*2 })
bin.sub!(/(.)\g1*$/, {|s1| r = s1; s1*2 })
printf("%5d| %s%s\n", offset, ' ' * (40 + offset), bin.tr('01','.#'))
bin = [l*3, 0.to(bin.len-3).map{|i| bin.substr(i, 3) }..., r*3 ].map { |t|
1 & (rule >> t.bin)
}.join
}
}
evolve(90, "010") |
http://rosettacode.org/wiki/Elementary_cellular_automaton/Infinite_length | Elementary cellular automaton/Infinite length | The purpose of this task is to create a version of an Elementary cellular automaton whose number of cells is only limited by the memory size of the computer.
To be precise, consider the state of the automaton to be made of an infinite number of cells, but with a bounded support. In other words, to describe the state of the automaton, you need a finite number of adjacent cells, along with their individual state, and you then consider that the individual state of each of all other cells is the negation of the closest individual cell among the previously defined finite number of cells.
Examples:
1 -> ..., 0, 0, 1, 0, 0, ...
0, 1 -> ..., 1, 1, 0, 1, 0, 0, ...
1, 0, 1 -> ..., 0, 0, 1, 0, 1, 0, 0, ...
More complex methods can be imagined, provided it is possible to somehow encode the infinite sections. But for this task we will stick to this simple version.
| #Tcl | Tcl | package require Tcl 8.6
oo::class create InfiniteElementaryAutomaton {
variable rules
# Decode the rule number to get a collection of state mapping rules.
# In effect, "compiles" the rule number
constructor {ruleNumber} {
set ins {111 110 101 100 011 010 001 000}
set bits [split [string range [format %08b $ruleNumber] end-7 end] ""]
foreach input {111 110 101 100 011 010 001 000} state $bits {
dict set rules $input $state
}
}
# Apply the rule to an automaton state to get a new automaton state.
# We wrap the edges; the state space is circular.
method evolve {left state right} {
set state [list $left {*}$state $right]
set len [llength $state]
for {set i -1;set j 0;set k 1} {$j < $len} {incr i;incr j;incr k} {
set a [expr {$i<0 ? $left : [lindex $state $i]}]
set b [lindex $state $j]
set c [expr {$k==$len ? $right : [lindex $state $k]}]
lappend result [dict get $rules $a$b$c]
}
return $result
}
method evolveEnd {endState} {
return [dict get $rules $endState$endState$endState]
}
# Simple driver method; omit the initial state to get a centred dot
method run {steps {initialState "010"}} {
set cap [string repeat "\u2026" $steps]
set s [split [string map ". 0 # 1" $initialState] ""]
set left [lindex $s 0]
set right [lindex $s end]
set s [lrange $s 1 end-1]
for {set i 0} {$i < $steps} {incr i} {
puts $cap[string map "0 . 1 #" $left[join $s ""]$right]$cap
set s [my evolve $left $s $right]
set left [my evolveEnd $left]
set right [my evolveEnd $right]
set cap [string range $cap 1 end]
}
puts $cap[string map "0 . 1 #" $left[join $s ""]$right]$cap
}
}
foreach num {90 30} {
puts "Rule ${num}:"
set rule [InfiniteElementaryAutomaton new $num]
$rule run 25
$rule destroy
} |
http://rosettacode.org/wiki/EKG_sequence_convergence | EKG sequence convergence | The sequence is from the natural numbers and is defined by:
a(1) = 1;
a(2) = Start = 2;
for n > 2, a(n) shares at least one prime factor with a(n-1) and is the smallest such natural number not already used.
The sequence is called the EKG sequence (after its visual similarity to an electrocardiogram when graphed).
Variants of the sequence can be generated starting 1, N where N is any natural number larger than one. For the purposes of this task let us call:
The sequence described above , starting 1, 2, ... the EKG(2) sequence;
the sequence starting 1, 3, ... the EKG(3) sequence;
... the sequence starting 1, N, ... the EKG(N) sequence.
Convergence
If an algorithm that keeps track of the minimum amount of numbers and their corresponding prime factors used to generate the next term is used, then this may be known as the generators essential state. Two EKG generators with differing starts can converge to produce the same sequence after initial differences.
EKG(N1) and EKG(N2) are said to to have converged at and after generation a(c) if state_of(EKG(N1).a(c)) == state_of(EKG(N2).a(c)).
Task
Calculate and show here the first 10 members of EKG(2).
Calculate and show here the first 10 members of EKG(5).
Calculate and show here the first 10 members of EKG(7).
Calculate and show here the first 10 members of EKG(9).
Calculate and show here the first 10 members of EKG(10).
Calculate and show here at which term EKG(5) and EKG(7) converge (stretch goal).
Related Tasks
Greatest common divisor
Sieve of Eratosthenes
Reference
The EKG Sequence and the Tree of Numbers. (Video).
| #XPL0 | XPL0 | int N, A(1+30);
func Used; int M; \Return 'true' if M is in array A
int I;
[for I:= 1 to N-1 do
if M = A(I) then return true;
return false;
];
func MinFactor; int Num; \Return minimum unused factor
int Fac, Val, Min;
[Fac:= 2;
Min:= -1>>1;
repeat if rem(Num/Fac) = 0 then \found a factor
[Val:= Fac;
loop [if Used(Val) then Val:= Val+Fac
else [if Val<Min then Min:= Val;
quit;
];
];
Num:= Num/Fac;
]
else Fac:= Fac+1;
until Fac > Num;
return Min;
];
proc EKG; int M; \Calculate and show EKG sequence
[A(1):= 1; A(2):= M;
for N:= 3 to 30 do
A(N):= MinFactor(A(N-1));
Format(2, 0);
Text(0, "EKG("); RlOut(0, float(M)); Text(0, "):");
Format(3, 0);
for N:= 1 to 30 do
RlOut(0, float(A(N)));
CrLf(0);
];
int Tbl, I;
[Tbl:= [2, 5, 7, 9, 10];
for I:= 0 to 4 do EKG(Tbl(I));
] |
http://rosettacode.org/wiki/EKG_sequence_convergence | EKG sequence convergence | The sequence is from the natural numbers and is defined by:
a(1) = 1;
a(2) = Start = 2;
for n > 2, a(n) shares at least one prime factor with a(n-1) and is the smallest such natural number not already used.
The sequence is called the EKG sequence (after its visual similarity to an electrocardiogram when graphed).
Variants of the sequence can be generated starting 1, N where N is any natural number larger than one. For the purposes of this task let us call:
The sequence described above , starting 1, 2, ... the EKG(2) sequence;
the sequence starting 1, 3, ... the EKG(3) sequence;
... the sequence starting 1, N, ... the EKG(N) sequence.
Convergence
If an algorithm that keeps track of the minimum amount of numbers and their corresponding prime factors used to generate the next term is used, then this may be known as the generators essential state. Two EKG generators with differing starts can converge to produce the same sequence after initial differences.
EKG(N1) and EKG(N2) are said to to have converged at and after generation a(c) if state_of(EKG(N1).a(c)) == state_of(EKG(N2).a(c)).
Task
Calculate and show here the first 10 members of EKG(2).
Calculate and show here the first 10 members of EKG(5).
Calculate and show here the first 10 members of EKG(7).
Calculate and show here the first 10 members of EKG(9).
Calculate and show here the first 10 members of EKG(10).
Calculate and show here at which term EKG(5) and EKG(7) converge (stretch goal).
Related Tasks
Greatest common divisor
Sieve of Eratosthenes
Reference
The EKG Sequence and the Tree of Numbers. (Video).
| #zkl | zkl | fcn ekgW(N){ // --> iterator
Walker.tweak(fcn(rp,buf,w){
foreach n in (w){
if(rp.value.gcd(n)>1)
{ rp.set(n); w.push(buf.xplode()); buf.clear(); return(n); }
buf.append(n); // save small numbers not used yet
}
}.fp(Ref(N),List(),Walker.chain([2..N-1],[N+1..]))).push(1,N)
} |
http://rosettacode.org/wiki/Empty_string | Empty string | Languages may have features for dealing specifically with empty strings
(those containing no characters).
Task
Demonstrate how to assign an empty string to a variable.
Demonstrate how to check that a string is empty.
Demonstrate how to check that a string is not empty.
Other tasks related to string operations:
Metrics
Array length
String length
Copy a string
Empty string (assignment)
Counting
Word frequency
Letter frequency
Jewels and stones
I before E except after C
Bioinformatics/base count
Count occurrences of a substring
Count how many vowels and consonants occur in a string
Remove/replace
XXXX redacted
Conjugate a Latin verb
Remove vowels from a string
String interpolation (included)
Strip block comments
Strip comments from a string
Strip a set of characters from a string
Strip whitespace from a string -- top and tail
Strip control codes and extended characters from a string
Anagrams/Derangements/shuffling
Word wheel
ABC problem
Sattolo cycle
Knuth shuffle
Ordered words
Superpermutation minimisation
Textonyms (using a phone text pad)
Anagrams
Anagrams/Deranged anagrams
Permutations/Derangements
Find/Search/Determine
ABC words
Odd words
Word ladder
Semordnilap
Word search
Wordiff (game)
String matching
Tea cup rim text
Alternade words
Changeable words
State name puzzle
String comparison
Unique characters
Unique characters in each string
Extract file extension
Levenshtein distance
Palindrome detection
Common list elements
Longest common suffix
Longest common prefix
Compare a list of strings
Longest common substring
Find common directory path
Words from neighbour ones
Change e letters to i in words
Non-continuous subsequences
Longest common subsequence
Longest palindromic substrings
Longest increasing subsequence
Words containing "the" substring
Sum of the digits of n is substring of n
Determine if a string is numeric
Determine if a string is collapsible
Determine if a string is squeezable
Determine if a string has all unique characters
Determine if a string has all the same characters
Longest substrings without repeating characters
Find words which contains all the vowels
Find words which contains most consonants
Find words which contains more than 3 vowels
Find words which first and last three letters are equals
Find words which odd letters are consonants and even letters are vowels or vice_versa
Formatting
Substring
Rep-string
Word wrap
String case
Align columns
Literals/String
Repeat a string
Brace expansion
Brace expansion using ranges
Reverse a string
Phrase reversals
Comma quibbling
Special characters
String concatenation
Substring/Top and tail
Commatizing numbers
Reverse words in a string
Suffixation of decimal numbers
Long literals, with continuations
Numerical and alphabetical suffixes
Abbreviations, easy
Abbreviations, simple
Abbreviations, automatic
Song lyrics/poems/Mad Libs/phrases
Mad Libs
Magic 8-ball
99 Bottles of Beer
The Name Game (a song)
The Old lady swallowed a fly
The Twelve Days of Christmas
Tokenize
Text between
Tokenize a string
Word break problem
Tokenize a string with escaping
Split a character string based on change of character
Sequences
Show ASCII table
De Bruijn sequences
Self-referential sequences
Generate lower case ASCII alphabet
| #Visual_Basic_.NET | Visual Basic .NET | Dim s As String
' Assign empty string:
s = ""
' or
s = String.Empty
' Check for empty string only (false if s is null):
If s IsNot Nothing AndAlso s.Length = 0 Then
End If
' Check for null or empty (more idiomatic in .NET):
If String.IsNullOrEmpty(s) Then
End If |
http://rosettacode.org/wiki/Empty_string | Empty string | Languages may have features for dealing specifically with empty strings
(those containing no characters).
Task
Demonstrate how to assign an empty string to a variable.
Demonstrate how to check that a string is empty.
Demonstrate how to check that a string is not empty.
Other tasks related to string operations:
Metrics
Array length
String length
Copy a string
Empty string (assignment)
Counting
Word frequency
Letter frequency
Jewels and stones
I before E except after C
Bioinformatics/base count
Count occurrences of a substring
Count how many vowels and consonants occur in a string
Remove/replace
XXXX redacted
Conjugate a Latin verb
Remove vowels from a string
String interpolation (included)
Strip block comments
Strip comments from a string
Strip a set of characters from a string
Strip whitespace from a string -- top and tail
Strip control codes and extended characters from a string
Anagrams/Derangements/shuffling
Word wheel
ABC problem
Sattolo cycle
Knuth shuffle
Ordered words
Superpermutation minimisation
Textonyms (using a phone text pad)
Anagrams
Anagrams/Deranged anagrams
Permutations/Derangements
Find/Search/Determine
ABC words
Odd words
Word ladder
Semordnilap
Word search
Wordiff (game)
String matching
Tea cup rim text
Alternade words
Changeable words
State name puzzle
String comparison
Unique characters
Unique characters in each string
Extract file extension
Levenshtein distance
Palindrome detection
Common list elements
Longest common suffix
Longest common prefix
Compare a list of strings
Longest common substring
Find common directory path
Words from neighbour ones
Change e letters to i in words
Non-continuous subsequences
Longest common subsequence
Longest palindromic substrings
Longest increasing subsequence
Words containing "the" substring
Sum of the digits of n is substring of n
Determine if a string is numeric
Determine if a string is collapsible
Determine if a string is squeezable
Determine if a string has all unique characters
Determine if a string has all the same characters
Longest substrings without repeating characters
Find words which contains all the vowels
Find words which contains most consonants
Find words which contains more than 3 vowels
Find words which first and last three letters are equals
Find words which odd letters are consonants and even letters are vowels or vice_versa
Formatting
Substring
Rep-string
Word wrap
String case
Align columns
Literals/String
Repeat a string
Brace expansion
Brace expansion using ranges
Reverse a string
Phrase reversals
Comma quibbling
Special characters
String concatenation
Substring/Top and tail
Commatizing numbers
Reverse words in a string
Suffixation of decimal numbers
Long literals, with continuations
Numerical and alphabetical suffixes
Abbreviations, easy
Abbreviations, simple
Abbreviations, automatic
Song lyrics/poems/Mad Libs/phrases
Mad Libs
Magic 8-ball
99 Bottles of Beer
The Name Game (a song)
The Old lady swallowed a fly
The Twelve Days of Christmas
Tokenize
Text between
Tokenize a string
Word break problem
Tokenize a string with escaping
Split a character string based on change of character
Sequences
Show ASCII table
De Bruijn sequences
Self-referential sequences
Generate lower case ASCII alphabet
| #Vlang | Vlang | // define and initialize an empty string
mut s := ""
// assign an empty string to a variable
s = ""
// check that a string is empty, any of:
s == ""
s.len() == 0
// check that a string is not empty, any of:
s != ""
s.len() != 0 // or > 0 |
http://rosettacode.org/wiki/Empty_program | Empty program | Task
Create the simplest possible program that is still considered "correct."
| #Scheme | Scheme | |
http://rosettacode.org/wiki/Empty_program | Empty program | Task
Create the simplest possible program that is still considered "correct."
| #Scilab | Scilab | |
http://rosettacode.org/wiki/Empty_program | Empty program | Task
Create the simplest possible program that is still considered "correct."
| #ScratchScript | ScratchScript | // |
http://rosettacode.org/wiki/Earliest_difference_between_prime_gaps | Earliest difference between prime gaps | When calculating prime numbers > 2, the difference between adjacent primes is always an even number. This difference, also referred to as the gap, varies in an random pattern; at least, no pattern has ever been discovered, and it is strongly conjectured that no pattern exists. However, it is also conjectured that between some two adjacent primes will be a gap corresponding to every positive even integer.
gap
minimal
starting
prime
ending
prime
2
3
5
4
7
11
6
23
29
8
89
97
10
139
149
12
199
211
14
113
127
16
1831
1847
18
523
541
20
887
907
22
1129
1151
24
1669
1693
26
2477
2503
28
2971
2999
30
4297
4327
This task involves locating the minimal primes corresponding to those gaps.
Though every gap value exists, they don't seem to come in any particular order. For example, this table shows the gaps and minimum starting value primes for 2 through 30:
For the purposes of this task, considering only primes greater than 2, consider prime gaps that differ by exactly two to be adjacent.
Task
For each order of magnitude m from 10¹ through 10⁶:
Find the first two sets of adjacent minimum prime gaps where the absolute value of the difference between the prime gap start values is greater than m.
E.G.
For an m of 10¹;
The start value of gap 2 is 3, the start value of gap 4 is 7, the difference is 7 - 3 or 4. 4 < 10¹ so keep going.
The start value of gap 4 is 7, the start value of gap 6 is 23, the difference is 23 - 7, or 16. 16 > 10¹ so this the earliest adjacent gap difference > 10¹.
Stretch goal
Do the same for 10⁷ and 10⁸ (and higher?) orders of magnitude
Note: the earliest value found for each order of magnitude may not be unique, in fact, is not unique; also, with the gaps in ascending order, the minimal starting values are not strictly ascending.
| #F.23 | F# |
// Earliest difference between prime gaps. Nigel Galloway: December 1st., 2021
let fN y=let i=System.Collections.Generic.SortedDictionary<int64,int64>()
let fN()=i|>Seq.pairwise|>Seq.takeWhile(fun(n,g)->g.Key=n.Key+2L)|>Seq.tryFind(fun(n,g)->abs(n.Value-g.Value)>y)
(fun(n,g)->let e=g-n in match i.TryGetValue(e) with (false,_)->i.Add(e,n); fN() |_->None)
[1..9]|>List.iter(fun g->let fN=fN(pown 10 g) in let n,i=(primes64()|>Seq.skip 1|>Seq.pairwise|>Seq.map fN|>Seq.find Option.isSome).Value
printfn $"%10d{pown 10 g} -> distance between start of gap %d{n.Key}=%d{n.Value} and start of gap %d{i.Key}=%d{i.Value} is %d{abs((n.Value)-(i.Value))}")
|
http://rosettacode.org/wiki/Earliest_difference_between_prime_gaps | Earliest difference between prime gaps | When calculating prime numbers > 2, the difference between adjacent primes is always an even number. This difference, also referred to as the gap, varies in an random pattern; at least, no pattern has ever been discovered, and it is strongly conjectured that no pattern exists. However, it is also conjectured that between some two adjacent primes will be a gap corresponding to every positive even integer.
gap
minimal
starting
prime
ending
prime
2
3
5
4
7
11
6
23
29
8
89
97
10
139
149
12
199
211
14
113
127
16
1831
1847
18
523
541
20
887
907
22
1129
1151
24
1669
1693
26
2477
2503
28
2971
2999
30
4297
4327
This task involves locating the minimal primes corresponding to those gaps.
Though every gap value exists, they don't seem to come in any particular order. For example, this table shows the gaps and minimum starting value primes for 2 through 30:
For the purposes of this task, considering only primes greater than 2, consider prime gaps that differ by exactly two to be adjacent.
Task
For each order of magnitude m from 10¹ through 10⁶:
Find the first two sets of adjacent minimum prime gaps where the absolute value of the difference between the prime gap start values is greater than m.
E.G.
For an m of 10¹;
The start value of gap 2 is 3, the start value of gap 4 is 7, the difference is 7 - 3 or 4. 4 < 10¹ so keep going.
The start value of gap 4 is 7, the start value of gap 6 is 23, the difference is 23 - 7, or 16. 16 > 10¹ so this the earliest adjacent gap difference > 10¹.
Stretch goal
Do the same for 10⁷ and 10⁸ (and higher?) orders of magnitude
Note: the earliest value found for each order of magnitude may not be unique, in fact, is not unique; also, with the gaps in ascending order, the minimal starting values are not strictly ascending.
| #Go | Go | package main
import (
"fmt"
"rcu"
)
func main() {
limit := int(1e9)
gapStarts := make(map[int]int)
primes := rcu.Primes(limit * 5)
for i := 1; i < len(primes); i++ {
gap := primes[i] - primes[i-1]
if _, ok := gapStarts[gap]; !ok {
gapStarts[gap] = primes[i-1]
}
}
pm := 10
gap1 := 2
for {
for _, ok := gapStarts[gap1]; !ok; {
gap1 += 2
}
start1 := gapStarts[gap1]
gap2 := gap1 + 2
if _, ok := gapStarts[gap2]; !ok {
gap1 = gap2 + 2
continue
}
start2 := gapStarts[gap2]
diff := start2 - start1
if diff < 0 {
diff = -diff
}
if diff > pm {
cpm := rcu.Commatize(pm)
cst1 := rcu.Commatize(start1)
cst2 := rcu.Commatize(start2)
cd := rcu.Commatize(diff)
fmt.Printf("Earliest difference > %s between adjacent prime gap starting primes:\n", cpm)
fmt.Printf("Gap %d starts at %s, gap %d starts at %s, difference is %s.\n\n", gap1, cst1, gap2, cst2, cd)
if pm == limit {
break
}
pm *= 10
} else {
gap1 = gap2
}
}
} |
http://rosettacode.org/wiki/Element-wise_operations | Element-wise operations | This task is similar to:
Matrix multiplication
Matrix transposition
Task
Implement basic element-wise matrix-matrix and scalar-matrix operations, which can be referred to in other, higher-order tasks.
Implement:
addition
subtraction
multiplication
division
exponentiation
Extend the task if necessary to include additional basic operations, which should not require their own specialised task.
| #BBC_BASIC | BBC BASIC | DIM a(1,2), b(1,2), c(1,2)
a() = 7, 8, 7, 4, 0, 9 : b() = 4, 5, 1, 6, 2, 1
REM Matrix-Matrix:
c() = a() + b() : PRINT FNshowmm(a(), "+", b(), c())
c() = a() - b() : PRINT FNshowmm(a(), "-", b(), c())
c() = a() * b() : PRINT FNshowmm(a(), "*", b(), c())
c() = a() / b() : PRINT FNshowmm(a(), "/", b(), c())
PROCpowmm(a(), b(), c()) : PRINT FNshowmm(a(), "^", b(), c()) '
REM Matrix-Scalar:
c() = a() + 3 : PRINT FNshowms(a(), "+", 3, c())
c() = a() - 3 : PRINT FNshowms(a(), "-", 3, c())
c() = a() * 3 : PRINT FNshowms(a(), "*", 3, c())
c() = a() / 3 : PRINT FNshowms(a(), "/", 3, c())
PROCpowms(a(), 3, c()) : PRINT FNshowms(a(), "^", 3, c())
END
DEF PROCpowmm(a(), b(), c())
LOCAL i%, j%
FOR i% = 0 TO DIM(a(),1)
FOR j% = 0 TO DIM(a(),2)
c(i%,j%) = a(i%,j%) ^ b(i%,j%)
NEXT
NEXT
ENDPROC
DEF PROCpowms(a(), b, c())
LOCAL i%, j%
FOR i% = 0 TO DIM(a(),1)
FOR j% = 0 TO DIM(a(),2)
c(i%,j%) = a(i%,j%) ^ b
NEXT
NEXT
ENDPROC
DEF FNshowmm(a(), op$, b(), c())
= FNlist(a()) + " " + op$ + " " + FNlist(b()) + " = " + FNlist(c())
DEF FNshowms(a(), op$, b, c())
= FNlist(a()) + " " + op$ + " " + STR$(b) + " = " + FNlist(c())
DEF FNlist(a())
LOCAL i%, j%, a$
a$ = "["
FOR i% = 0 TO DIM(a(),1)
a$ += "["
FOR j% = 0 TO DIM(a(),2)
a$ += STR$(a(i%,j%)) + ", "
NEXT
a$ = LEFT$(LEFT$(a$)) + "]"
NEXT
= a$ + "]" |
http://rosettacode.org/wiki/Egyptian_division | Egyptian division | Egyptian division is a method of dividing integers using addition and
doubling that is similar to the algorithm of Ethiopian multiplication
Algorithm:
Given two numbers where the dividend is to be divided by the divisor:
Start the construction of a table of two columns: powers_of_2, and doublings; by a first row of a 1 (i.e. 2^0) in the first column and 1 times the divisor in the first row second column.
Create the second row with columns of 2 (i.e 2^1), and 2 * divisor in order.
Continue with successive i’th rows of 2^i and 2^i * divisor.
Stop adding rows, and keep only those rows, where 2^i * divisor is less than or equal to the dividend.
We now assemble two separate sums that both start as zero, called here answer and accumulator
Consider each row of the table, in the reverse order of its construction.
If the current value of the accumulator added to the doublings cell would be less than or equal to the dividend then add it to the accumulator, as well as adding the powers_of_2 cell value to the answer.
When the first row has been considered as above, then the integer division of dividend by divisor is given by answer.
(And the remainder is given by the absolute value of accumulator - dividend).
Example: 580 / 34
Table creation:
powers_of_2
doublings
1
34
2
68
4
136
8
272
16
544
Initialization of sums:
powers_of_2
doublings
answer
accumulator
1
34
2
68
4
136
8
272
16
544
0
0
Considering table rows, bottom-up:
When a row is considered it is shown crossed out if it is not accumulated, or bold if the row causes summations.
powers_of_2
doublings
answer
accumulator
1
34
2
68
4
136
8
272
16
544
16
544
powers_of_2
doublings
answer
accumulator
1
34
2
68
4
136
8
272
16
544
16
544
powers_of_2
doublings
answer
accumulator
1
34
2
68
4
136
16
544
8
272
16
544
powers_of_2
doublings
answer
accumulator
1
34
2
68
16
544
4
136
8
272
16
544
powers_of_2
doublings
answer
accumulator
1
34
17
578
2
68
4
136
8
272
16
544
Answer
So 580 divided by 34 using the Egyptian method is 17 remainder (578 - 580) or 2.
Task
The task is to create a function that does Egyptian division. The function should
closely follow the description above in using a list/array of powers of two, and
another of doublings.
Functions should be clear interpretations of the algorithm.
Use the function to divide 580 by 34 and show the answer here, on this page.
Related tasks
Egyptian fractions
References
Egyptian Number System
| #AppleScript | AppleScript | -- EGYPTIAN DIVISION ------------------------------------
-- eqyptianQuotRem :: Int -> Int -> (Int, Int)
on egyptianQuotRem(m, n)
script expansion
on |λ|(ix)
set {i, x} to ix
if x > m then
Nothing()
else
Just({ix, {i + i, x + x}})
end if
end |λ|
end script
script collapse
on |λ|(ix, qr)
set {i, x} to ix
set {q, r} to qr
if x < r then
{q + i, r - x}
else
qr
end if
end |λ|
end script
return foldr(collapse, {0, m}, ¬
unfoldr(expansion, {1, n}))
end egyptianQuotRem
-- TEST -------------------------------------------------
on run
egyptianQuotRem(580, 34)
end run
-- GENERIC FUNCTIONS ------------------------------------
-- Just :: a -> Maybe a
on Just(x)
{type:"Maybe", Nothing:false, Just:x}
end Just
-- Nothing :: Maybe a
on Nothing()
{type:"Maybe", Nothing:true}
end Nothing
-- foldr :: (a -> b -> b) -> b -> [a] -> b
on foldr(f, startValue, xs)
tell mReturn(f)
set v to startValue
set lng to length of xs
repeat with i from lng to 1 by -1
set v to |λ|(item i of xs, v, i, xs)
end repeat
return v
end tell
end foldr
-- Lift 2nd class handler function into 1st class script wrapper
-- mReturn :: First-class m => (a -> b) -> m (a -> b)
on mReturn(f)
if class of f is script then
f
else
script
property |λ| : f
end script
end if
end mReturn
-- > unfoldr (\b -> if b == 0 then Nothing else Just (b, b-1)) 10
-- > [10,9,8,7,6,5,4,3,2,1]
-- unfoldr :: (b -> Maybe (a, b)) -> b -> [a]
on unfoldr(f, v)
set xr to {v, v} -- (value, remainder)
set xs to {}
tell mReturn(f)
repeat -- Function applied to remainder.
set mb to |λ|(item 2 of xr)
if Nothing of mb then
exit repeat
else -- New (value, remainder) tuple,
set xr to Just of mb
-- and value appended to output list.
set end of xs to item 1 of xr
end if
end repeat
end tell
return xs
end unfoldr |
http://rosettacode.org/wiki/Egyptian_fractions | Egyptian fractions | An Egyptian fraction is the sum of distinct unit fractions such as:
1
2
+
1
3
+
1
16
(
=
43
48
)
{\displaystyle {\tfrac {1}{2}}+{\tfrac {1}{3}}+{\tfrac {1}{16}}\,(={\tfrac {43}{48}})}
Each fraction in the expression has a numerator equal to 1 (unity) and a denominator that is a positive integer, and all the denominators are distinct (i.e., no repetitions).
Fibonacci's Greedy algorithm for Egyptian fractions expands the fraction
x
y
{\displaystyle {\tfrac {x}{y}}}
to be represented by repeatedly performing the replacement
x
y
=
1
⌈
y
/
x
⌉
+
(
−
y
)
mod
x
y
⌈
y
/
x
⌉
{\displaystyle {\frac {x}{y}}={\frac {1}{\lceil y/x\rceil }}+{\frac {(-y)\!\!\!\!\mod x}{y\lceil y/x\rceil }}}
(simplifying the 2nd term in this replacement as necessary, and where
⌈
x
⌉
{\displaystyle \lceil x\rceil }
is the ceiling function).
For this task, Proper and improper fractions must be able to be expressed.
Proper fractions are of the form
a
b
{\displaystyle {\tfrac {a}{b}}}
where
a
{\displaystyle a}
and
b
{\displaystyle b}
are positive integers, such that
a
<
b
{\displaystyle a<b}
, and
improper fractions are of the form
a
b
{\displaystyle {\tfrac {a}{b}}}
where
a
{\displaystyle a}
and
b
{\displaystyle b}
are positive integers, such that a ≥ b.
(See the REXX programming example to view one method of expressing the whole number part of an improper fraction.)
For improper fractions, the integer part of any improper fraction should be first isolated and shown preceding the Egyptian unit fractions, and be surrounded by square brackets [n].
Task requirements
show the Egyptian fractions for:
43
48
{\displaystyle {\tfrac {43}{48}}}
and
5
121
{\displaystyle {\tfrac {5}{121}}}
and
2014
59
{\displaystyle {\tfrac {2014}{59}}}
for all proper fractions,
a
b
{\displaystyle {\tfrac {a}{b}}}
where
a
{\displaystyle a}
and
b
{\displaystyle b}
are positive one-or two-digit (decimal) integers, find and show an Egyptian fraction that has:
the largest number of terms,
the largest denominator.
for all one-, two-, and three-digit integers, find and show (as above). {extra credit}
Also see
Wolfram MathWorld™ entry: Egyptian fraction
| #ALGOL_68 | ALGOL 68 | BEGIN # compute some Egytian fractions #
PR precision 2000 PR # set the number of digits for LONG LONG INT #
PROC gcd = ( LONG LONG INT a, b )LONG LONG INT:
IF b = 0 THEN
IF a < 0 THEN
- a
ELSE
a
FI
ELSE
gcd( b, a MOD b )
FI ; # gcd #
MODE RATIONAL = STRUCT( LONG LONG INT num, den );
MODE LISTOFRATIONAL = STRUCT( RATIONAL element, REF LISTOFRATIONAL next );
REF LISTOFRATIONAL nil list of rational = NIL;
OP TOSTRING = ( INT a )STRING: whole( a, 0 );
OP TOSTRING = ( LONG INT a )STRING: whole( a, 0 );
OP TOSTRING = ( LONG LONG INT a )STRING: whole( a, 0 );
OP TOSTRING = ( RATIONAL a )STRING:
IF den OF a = 1
THEN TOSTRING num OF a
ELSE TOSTRING num OF a + "/" + TOSTRING den OF a
FI ; # TOSTRING #
OP TOSTRING = ( REF LISTOFRATIONAL lr )STRING:
BEGIN
REF LISTOFRATIONAL p := lr;
STRING result := "[";
WHILE p ISNT nil list of rational DO
result +:= TOSTRING element OF p;
IF next OF p IS nil list of rational THEN
p := NIL
ELSE
p := next OF p;
result +:= " + "
FI
OD;
result + "]"
END ; # TOSTRING #
OP CEIL = ( LONG LONG REAL v )LONG LONG INT:
IF LONG LONG INT result := ENTIER v;
ABS v > ABS result
THEN result + 1
ELSE result
FI ; # CEIL #
OP EGYPTIAN = ( RATIONAL rp )REF LISTOFRATIONAL:
IF RATIONAL r := rp;
num OF r = 0 OR num OF r = 1
THEN HEAP LISTOFRATIONAL := ( r, nil list of rational )
ELSE
REF LISTOFRATIONAL result := nil list of rational;
REF LISTOFRATIONAL end result := nil list of rational;
PROC add = ( RATIONAL r )VOID:
IF end result IS nil list of rational THEN
result := HEAP LISTOFRATIONAL := ( r, nil list of rational );
end result := result
ELSE
next OF end result := HEAP LISTOFRATIONAL := ( r, nil list of rational );
end result := next OF end result
FI ; # add #
IF num OF r > den OF r THEN
add( RATIONAL( num OF r OVER den OF r, 1 ) );
r := ( num OF r MOD den OF r, den OF r )
FI;
PROC mod func = ( LONG LONG INT m, n )LONG LONG INT: ( ( m MOD n ) + n ) MOD n;
WHILE num OF r /= 0 DO
LONG LONG INT q = CEIL( den OF r / num OF r );
add( RATIONAL( 1, q ) );
r := RATIONAL( mod func( - ( den OF r ), num OF r ), ( den OF r ) * q )
OD;
result
FI ; # EGYPTIAN #
BEGIN # task test cases #
[]RATIONAL test cases = ( RATIONAL( 43, 48 ), RATIONAL( 5, 121 ), RATIONAL( 2014, 59 ) );
FOR r pos FROM LWB test cases TO UPB test cases DO
print( ( TOSTRING test cases[ r pos ], " -> ", TOSTRING EGYPTIAN test cases[ r pos ], newline ) )
OD;
# find the fractions with the most terms and the largest denominator #
print( ( "For rationals with numerator and denominator in 1..99:", newline ) );
RATIONAL largest denominator := ( 0, 1 );
REF LISTOFRATIONAL max denominator list := nil list of rational;
LONG LONG INT max denominator := 0;
RATIONAL most terms := ( 0, 1 );
REF LISTOFRATIONAL most terms list := nil list of rational;
INT max terms := 0;
FOR num TO 99 DO
FOR den TO 99 DO
RATIONAL r = RATIONAL( num, den );
REF LISTOFRATIONAL e := EGYPTIAN r;
REF LISTOFRATIONAL p := e;
INT terms := 0;
WHILE p ISNT nil list of rational DO
terms +:= 1;
IF den OF element OF p > max denominator THEN
largest denominator := r;
max denominator := den OF element OF p;
max denominator list := e
FI;
p := next OF p
OD;
IF terms > max terms THEN
most terms := r;
max terms := terms;
most terms list := e
FI
OD
OD;
print( ( " ", TOSTRING most terms, " has the most terms: ", TOSTRING max terms, newline
, " ", TOSTRING most terms list, newline
)
);
print( ( " ", TOSTRING largest denominator, " has the largest denominator:", newline
, " ", TOSTRING max denominator list, newline
)
)
END
END |
http://rosettacode.org/wiki/Eertree | Eertree | An eertree is a data structure designed for efficient processing of certain palindrome tasks, for instance counting the number of sub-palindromes in an input string.
The data structure has commonalities to both tries and suffix trees.
See links below.
Task
Construct an eertree for the string "eertree", then output all sub-palindromes by traversing the tree.
See also
Wikipedia entry: trie.
Wikipedia entry: suffix tree
Cornell University Library, Computer Science, Data Structures and Algorithms ───► EERTREE: An Efficient Data Structure for Processing Palindromes in Strings.
| #M2000_Interpreter | M2000 Interpreter |
If Version<9.5 Then exit
If Version=9.5 And Revision<2 Then Exit
Class Node {
inventory myedges
length, suffix=0
Function edges(s$) {
=-1 : if exist(.myedges, s$) then =eval(.myedges)
}
Module edges_append (a$, where) {
Append .myedges, a$:=where
}
Class:
Module Node(.length) {
Read ? .suffix, .myedges
}
}
function eertree(s$) {
Const evenRoot=0, oddRoot=1
Inventory Tree= oddRoot:=Node(-1,1),evenRoot:=Node(0,1)
k=0
suffix=oddRoot
for i=0 to len(s$)-1 {
c$=mid$(s$,i+1,1)
n=suffix
Do {
k=tree(n).length
b=i-k-1
if b>=0 then if mid$(s$,b+1,1)=c$ Then exit
n =tree(n).suffix
} Always
e=tree(n).edges(c$)
if e>=0 then suffix=e :continue
suffix=len(Tree)
Append Tree, len(Tree):=Node(k+2)
Tree(n).edges_append c$, suffix
If tree(suffix).length=1 then tree(suffix).suffix=0 : continue
Do {
n=tree(n).suffix
b=i-tree(n).length-1
if b>0 Then If mid$(s$, b+1,1)=c$ then exit
} Always
e=tree(n).edges(c$)
if e>=0 then tree(suffix).suffix=e
}
=tree
}
children=lambda (s, tree, n, root$="")->{
L=Len(tree(n).myEdges)
if L=0 then =s : exit
L--
For i=0 to L {
c=tree(n).myEdges
c$=Eval$(c, i) ' read keys at position i
nxt=c(i!) ' read value using position
p$ = if$(n=1 -> c$, c$+root$+c$)
append s, (p$,)
\\ better use lambda() and not children()
\\ for recursion when we copy this lambda to other identifier.
s = lambda(s, tree, nxt, p$)
}
= s
}
aString=Lambda ->{
Push Quote$(Letter$)
}
aLine=Lambda ->{
Shift 2 ' swap two top stack items
if stackitem$()="" then { Drop} Else Push letter$+", "+Letter$
}
Palindromes$=Lambda$ children, aString, aLine (Tree)-> {
="("+children(children((,), Tree, 0), Tree, 1)#Map(aString)#Fold$(aline,"")+")"
}
Print Palindromes$(eertree("eertree"))
|
http://rosettacode.org/wiki/Eertree | Eertree | An eertree is a data structure designed for efficient processing of certain palindrome tasks, for instance counting the number of sub-palindromes in an input string.
The data structure has commonalities to both tries and suffix trees.
See links below.
Task
Construct an eertree for the string "eertree", then output all sub-palindromes by traversing the tree.
See also
Wikipedia entry: trie.
Wikipedia entry: suffix tree
Cornell University Library, Computer Science, Data Structures and Algorithms ───► EERTREE: An Efficient Data Structure for Processing Palindromes in Strings.
| #Nim | Nim | import algorithm, strformat, strutils, tables
type
Node = ref object
edges: Table[char, Node] # Edges (forward links).
link: Node # Suffix link (backward link).
len: int # Length of the node.
Eertree = object
nodes: seq[Node]
rto: Node # Odd length root node or node -1.
rte: Node # Even length root node or node 0.Node
str: string # Accumulated input string.
maxSuf: Node # Maximum suffix.
#---------------------------------------------------------------------------------------------------
func initEertree(): Eertree =
## Create and initialize an eertree.
result = Eertree(rto: Node(len: - 1), rte: Node(len: 0))
result.rto.link = result.rto
result.rte.link = result.rto
result.str = "0"
result.maxSuf = result.rte
#---------------------------------------------------------------------------------------------------
func getMaxSuffixPal(tree: Eertree; startNode: Node; ch: char): Node =
## We traverse the suffix-palindromes of "tree" in the order of decreasing length.
## For each palindrome we read its length "k" and compare "tree[i-k]" against "ch"
## until we get an equality or arrive at the -1 node.
result = startNode
let i = tree.str.high
while result != tree.rto and tree.str[i - result.len] != ch:
doAssert(result != result.link, "circular reference above odd root")
result = result.link
#---------------------------------------------------------------------------------------------------
func add(tree: var Eertree; ch: char): bool =
## We need to find the maximum suffix-palindrome P of Ta.
## Start by finding maximum suffix-palindrome Q of T.
## To do this, we traverse the suffix-palindromes of T
## in the order of decreasing length, starting with maxSuf(T).
let q = tree.getMaxSuffixPal(tree.maxSuf, ch)
# We check "q" to see whether it has an outgoing edge labeled by "ch".
result = ch notin q.edges
if result:
# We create the node "p" of length "q.len + 2"
let p = Node()
tree.nodes.add(p)
p.len = q.len + 2
if p.len == 1:
# If p = ch, create the suffix link (p, 0).
p.link = tree.rte
else:
# It remains to create the suffix link from "p" if "|p|>1". Just continue
# traversing suffix-palindromes of T starting with the suffix link of "q".
p.link = tree.getMaxSuffixPal(q.link, ch).edges[ch]
# Create the edge "(q, p)".
q.edges[ch] = p
# "p" becomes the new maxSuf.
tree.maxSuf = q.edges[ch]
# Store accumulated input string.
tree.str.add(ch)
#---------------------------------------------------------------------------------------------------
func getSubPalindromes(tree: Eertree; node: Node;
nodesToHere: seq[Node]; charsToHere: string;
result: var seq[string]) =
## Each node represents a palindrome, which can be reconstructed
## by the path from the root node to each non-root node.
# Traverse all edges, since they represent other palindromes.
for linkName, node2 in node.edges.pairs:
tree.getSubPalindromes(node2, nodesToHere & node2, charsToHere & linkName, result)
# Reconstruct based on charsToHere characters.
if node notin [tree.rto, tree.rte]:
# Don’t print for root nodes.
let assembled = reversed(charsTohere).join() &
(if nodesToHere[0] == tree.rte: charsToHere
else: charsToHere[1..^1])
result.add(assembled)
#---------------------------------------------------------------------------------------------------
func getSubPalindromes(tree: Eertree): seq[string] =
## Traverse tree to find sub-palindromes.
# Odd length words
tree.getSubPalindromes(tree.rto, @[tree.rto], "", result)
# Even length words
tree.getSubPalindromes(tree.rte, @[tree.rte], "", result)
#———————————————————————————————————————————————————————————————————————————————————————————————————
when isMainModule:
const Str = "eertree"
echo fmt"Processing string: '{Str}'"
var eertree = initEertree()
for ch in Str:
discard eertree.add(ch)
echo fmt"Number of sub-palindromes: {eertree.nodes.len}"
let result = eertree.getSubPalindromes()
echo fmt"Sub-palindromes: {result.join("", "")}" |
http://rosettacode.org/wiki/Ethiopian_multiplication | Ethiopian multiplication | Ethiopian multiplication is a method of multiplying integers using only addition, doubling, and halving.
Method:
Take two numbers to be multiplied and write them down at the top of two columns.
In the left-hand column repeatedly halve the last number, discarding any remainders, and write the result below the last in the same column, until you write a value of 1.
In the right-hand column repeatedly double the last number and write the result below. stop when you add a result in the same row as where the left hand column shows 1.
Examine the table produced and discard any row where the value in the left column is even.
Sum the values in the right-hand column that remain to produce the result of multiplying the original two numbers together
For example: 17 × 34
17 34
Halving the first column:
17 34
8
4
2
1
Doubling the second column:
17 34
8 68
4 136
2 272
1 544
Strike-out rows whose first cell is even:
17 34
8 68
4 136
2 272
1 544
Sum the remaining numbers in the right-hand column:
17 34
8 --
4 ---
2 ---
1 544
====
578
So 17 multiplied by 34, by the Ethiopian method is 578.
Task
The task is to define three named functions/methods/procedures/subroutines:
one to halve an integer,
one to double an integer, and
one to state if an integer is even.
Use these functions to create a function that does Ethiopian multiplication.
References
Ethiopian multiplication explained (BBC Video clip)
A Night Of Numbers - Go Forth And Multiply (Video)
Russian Peasant Multiplication
Programming Praxis: Russian Peasant Multiplication
| #Prolog | Prolog | halve(X,Y) :- Y is X // 2.
double(X,Y) :- Y is 2*X.
is_even(X) :- 0 is X mod 2.
% columns(First,Second,Left,Right) is true if integers First and Second
% expand into the columns Left and Right, respectively
columns(1,Second,[1],[Second]).
columns(First,Second,[First|Left],[Second|Right]) :-
halve(First,Halved),
double(Second,Doubled),
columns(Halved,Doubled,Left,Right).
% contribution(Left,Right,Amount) is true if integers Left and Right,
% from their respective columns contribute Amount to the final sum.
contribution(Left,_Right,0) :-
is_even(Left).
contribution(Left,Right,Right) :-
\+ is_even(Left).
ethiopian(First,Second,Product) :-
columns(First,Second,Left,Right),
maplist(contribution,Left,Right,Contributions),
sumlist(Contributions,Product). |
http://rosettacode.org/wiki/Elementary_cellular_automaton | Elementary cellular automaton | An elementary cellular automaton is a one-dimensional cellular automaton where there are two possible states (labeled 0 and 1) and the rule to determine the state of a cell in the next generation depends only on the current state of the cell and its two immediate neighbors. Those three values can be encoded with three bits.
The rules of evolution are then encoded with eight bits indicating the outcome of each of the eight possibilities 111, 110, 101, 100, 011, 010, 001 and 000 in this order. Thus for instance the rule 13 means that a state is updated to 1 only in the cases 011, 010 and 000, since 13 in binary is 0b00001101.
Task
Create a subroutine, program or function that allows to create and visualize the evolution of any of the 256 possible elementary cellular automaton of arbitrary space length and for any given initial state. You can demonstrate your solution with any automaton of your choice.
The space state should wrap: this means that the left-most cell should be considered as the right neighbor of the right-most cell, and reciprocally.
This task is basically a generalization of one-dimensional cellular automata.
See also
Cellular automata (natureofcode.com)
| #Ceylon | Ceylon | class Rule(number) satisfies Correspondence<Boolean[3], Boolean> {
shared Byte number;
"all 3 bit patterns will return a value so this is always true"
shared actual Boolean defines(Boolean[3] key) => true;
shared actual Boolean? get(Boolean[3] key) =>
number.get((key[0] then 4 else 0) + (key[1] then 2 else 0) + (key[2] then 1 else 0));
function binaryString(Integer integer, Integer maxPadding) =>
Integer.format(integer, 2).padLeading(maxPadding, '0');
string =>
let (digits = binaryString(number.unsigned, 8))
"Rule #``number``
``" | ".join { for (pattern in $111..0) binaryString(pattern, 3) }``
``" | ".join(digits.map((Character element) => element.string.pad(3)))``";
}
class ElementaryAutomaton {
shared static ElementaryAutomaton|ParseException parse(Rule rule, String cells, Character aliveChar, Character deadChar) {
if (!cells.every((Character element) => element == aliveChar || element == deadChar)) {
return ParseException("the string was not a valid automaton");
}
return ElementaryAutomaton(rule, cells.map((Character element) => element == aliveChar));
}
shared Rule rule;
Array<Boolean> cells;
shared new(Rule rule, {Boolean*} initialCells) {
this.rule = rule;
this.cells = Array { *initialCells };
}
shared Boolean evolve() {
if (cells.empty) {
return false;
}
function left(Integer index) {
assert (exists cell = cells[index - 1] else cells.last);
return cell;
}
function right(Integer index) {
assert (exists cell = cells[index + 1] else cells.first);
return cell;
}
value newCells = Array.ofSize(cells.size, false);
for (index->cell in cells.indexed) {
value neighbourhood = [left(index), cell, right(index)];
assert (exists newCell = rule[neighbourhood]);
newCells[index] = newCell;
}
if (newCells == cells) {
return false;
}
newCells.copyTo(cells);
return true;
}
shared void display(Character aliveChar = '#', Character deadChar = ' ') {
print("".join(cells.map((Boolean element) => element then aliveChar else deadChar)));
}
}
shared void run() {
value rule = Rule(90.byte);
print(rule);
value automaton = ElementaryAutomaton.parse(rule, " # ", '#', ' ');
assert (is ElementaryAutomaton automaton);
for (generation in 0..10) {
automaton.display();
automaton.evolve();
}
} |
http://rosettacode.org/wiki/Elementary_cellular_automaton | Elementary cellular automaton | An elementary cellular automaton is a one-dimensional cellular automaton where there are two possible states (labeled 0 and 1) and the rule to determine the state of a cell in the next generation depends only on the current state of the cell and its two immediate neighbors. Those three values can be encoded with three bits.
The rules of evolution are then encoded with eight bits indicating the outcome of each of the eight possibilities 111, 110, 101, 100, 011, 010, 001 and 000 in this order. Thus for instance the rule 13 means that a state is updated to 1 only in the cases 011, 010 and 000, since 13 in binary is 0b00001101.
Task
Create a subroutine, program or function that allows to create and visualize the evolution of any of the 256 possible elementary cellular automaton of arbitrary space length and for any given initial state. You can demonstrate your solution with any automaton of your choice.
The space state should wrap: this means that the left-most cell should be considered as the right neighbor of the right-most cell, and reciprocally.
This task is basically a generalization of one-dimensional cellular automata.
See also
Cellular automata (natureofcode.com)
| #Common_Lisp | Common Lisp | (defun automaton (init rule &optional (stop 10))
(labels ((next-gen (cells)
(mapcar #'new-cell
(cons (car (last cells)) cells)
cells
(append (cdr cells) (list (car cells)))))
(new-cell (left current right)
(let ((shift (+ (* left 4) (* current 2) right)))
(if (logtest rule (ash 1 shift)) 1 0)))
(pretty-print (cells)
(format T "~{~a~}~%"
(mapcar (lambda (x) (if (zerop x) #\. #\#))
cells))))
(loop for cells = init then (next-gen cells)
for i below stop
do (pretty-print cells))))
(automaton '(0 0 0 0 0 0 1 0 0 0 0 0 0) 90) |
http://rosettacode.org/wiki/Factorial | Factorial | Definitions
The factorial of 0 (zero) is defined as being 1 (unity).
The Factorial Function of a positive integer, n, is defined as the product of the sequence:
n, n-1, n-2, ... 1
Task
Write a function to return the factorial of a number.
Solutions can be iterative or recursive.
Support for trapping negative n errors is optional.
Related task
Primorial numbers
| #Symsyn | Symsyn |
fact
if n < 1
return
endif
* n fn fn
- n
call fact
return
start
if i < 20
1 fn
i n
call fact
fn []
+ i
goif
endif
|
http://rosettacode.org/wiki/Even_or_odd | Even or odd | Task
Test whether an integer is even or odd.
There is more than one way to solve this task:
Use the even and odd predicates, if the language provides them.
Check the least significant digit. With binary integers, i bitwise-and 1 equals 0 iff i is even, or equals 1 iff i is odd.
Divide i by 2. The remainder equals 0 iff i is even. The remainder equals +1 or -1 iff i is odd.
Use modular congruences:
i ≡ 0 (mod 2) iff i is even.
i ≡ 1 (mod 2) iff i is odd.
| #TI-83_BASIC | TI-83 BASIC |
If fPart(.5Ans
Then
Disp "ODD
Else
Disp "EVEN
End
|
http://rosettacode.org/wiki/Even_or_odd | Even or odd | Task
Test whether an integer is even or odd.
There is more than one way to solve this task:
Use the even and odd predicates, if the language provides them.
Check the least significant digit. With binary integers, i bitwise-and 1 equals 0 iff i is even, or equals 1 iff i is odd.
Divide i by 2. The remainder equals 0 iff i is even. The remainder equals +1 or -1 iff i is odd.
Use modular congruences:
i ≡ 0 (mod 2) iff i is even.
i ≡ 1 (mod 2) iff i is odd.
| #TUSCRIPT | TUSCRIPT | $$ MODE TUSCRIPT
LOOP n=-5,5
x=MOD(n,2)
SELECT x
CASE 0
PRINT n," is even"
DEFAULT
PRINT n," is odd"
ENDSELECT
ENDLOOP |
http://rosettacode.org/wiki/Echo_server | Echo server | Create a network service that sits on TCP port 12321, which accepts connections on that port, and which echoes complete lines (using a carriage-return/line-feed sequence as line separator) back to clients. No error handling is required. For the purposes of testing, it is only necessary to support connections from localhost (127.0.0.1 or perhaps ::1). Logging of connection information to standard output is recommended.
The implementation must be able to handle simultaneous connections from multiple clients. A multi-threaded or multi-process solution may be used. Each connection must be able to echo more than a single line.
The implementation must not stop responding to other clients if one client sends a partial line or stops reading responses.
| #Elixir | Elixir | defmodule Echo.Server do
def start(port) do
tcp_options = [:binary, {:packet, 0}, {:active, false}]
{:ok, socket} = :gen_tcp.listen(port, tcp_options)
listen(socket)
end
defp listen(socket) do
{:ok, conn} = :gen_tcp.accept(socket)
spawn(fn -> recv(conn) end)
listen(socket)
end
defp recv(conn) do
case :gen_tcp.recv(conn, 0) do
{:ok, data} ->
:gen_tcp.send(conn, data)
recv(conn)
{:error, :closed} ->
:ok
end
end
end
|
http://rosettacode.org/wiki/Elementary_cellular_automaton/Infinite_length | Elementary cellular automaton/Infinite length | The purpose of this task is to create a version of an Elementary cellular automaton whose number of cells is only limited by the memory size of the computer.
To be precise, consider the state of the automaton to be made of an infinite number of cells, but with a bounded support. In other words, to describe the state of the automaton, you need a finite number of adjacent cells, along with their individual state, and you then consider that the individual state of each of all other cells is the negation of the closest individual cell among the previously defined finite number of cells.
Examples:
1 -> ..., 0, 0, 1, 0, 0, ...
0, 1 -> ..., 1, 1, 0, 1, 0, 0, ...
1, 0, 1 -> ..., 0, 0, 1, 0, 1, 0, 0, ...
More complex methods can be imagined, provided it is possible to somehow encode the infinite sections. But for this task we will stick to this simple version.
| #Wren | Wren | import "/fmt" for Fmt
var addNoCells = Fn.new { |s|
var l = (s[0] == "*") ? "." : "*"
var r = (s[-1] == "*") ? "." : "*"
for (i in 0..1) {
s.insert(0, l)
s.add(r)
}
}
var step = Fn.new { |cells, rule|
var newCells = []
for (i in 0...cells.count - 2) {
var bin = 0
var b = 2
for (n in i...i + 3) {
bin = bin + (((cells[n] == "*") ? 1 : 0) << b)
b = b >> 1
}
var a = ((rule & (1 << bin)) != 0) ? "*" : "."
newCells.add(a)
}
return newCells
}
var evolve = Fn.new { |l, rule|
System.print(" Rule #%(rule):")
var cells = ["*"]
for (x in 0...l) {
addNoCells.call(cells)
var width = 40 + (cells.count >> 1)
Fmt.print("$*s", width, cells.join())
cells = step.call(cells, rule)
}
}
evolve.call(35, 90)
System.print() |
http://rosettacode.org/wiki/Empty_string | Empty string | Languages may have features for dealing specifically with empty strings
(those containing no characters).
Task
Demonstrate how to assign an empty string to a variable.
Demonstrate how to check that a string is empty.
Demonstrate how to check that a string is not empty.
Other tasks related to string operations:
Metrics
Array length
String length
Copy a string
Empty string (assignment)
Counting
Word frequency
Letter frequency
Jewels and stones
I before E except after C
Bioinformatics/base count
Count occurrences of a substring
Count how many vowels and consonants occur in a string
Remove/replace
XXXX redacted
Conjugate a Latin verb
Remove vowels from a string
String interpolation (included)
Strip block comments
Strip comments from a string
Strip a set of characters from a string
Strip whitespace from a string -- top and tail
Strip control codes and extended characters from a string
Anagrams/Derangements/shuffling
Word wheel
ABC problem
Sattolo cycle
Knuth shuffle
Ordered words
Superpermutation minimisation
Textonyms (using a phone text pad)
Anagrams
Anagrams/Deranged anagrams
Permutations/Derangements
Find/Search/Determine
ABC words
Odd words
Word ladder
Semordnilap
Word search
Wordiff (game)
String matching
Tea cup rim text
Alternade words
Changeable words
State name puzzle
String comparison
Unique characters
Unique characters in each string
Extract file extension
Levenshtein distance
Palindrome detection
Common list elements
Longest common suffix
Longest common prefix
Compare a list of strings
Longest common substring
Find common directory path
Words from neighbour ones
Change e letters to i in words
Non-continuous subsequences
Longest common subsequence
Longest palindromic substrings
Longest increasing subsequence
Words containing "the" substring
Sum of the digits of n is substring of n
Determine if a string is numeric
Determine if a string is collapsible
Determine if a string is squeezable
Determine if a string has all unique characters
Determine if a string has all the same characters
Longest substrings without repeating characters
Find words which contains all the vowels
Find words which contains most consonants
Find words which contains more than 3 vowels
Find words which first and last three letters are equals
Find words which odd letters are consonants and even letters are vowels or vice_versa
Formatting
Substring
Rep-string
Word wrap
String case
Align columns
Literals/String
Repeat a string
Brace expansion
Brace expansion using ranges
Reverse a string
Phrase reversals
Comma quibbling
Special characters
String concatenation
Substring/Top and tail
Commatizing numbers
Reverse words in a string
Suffixation of decimal numbers
Long literals, with continuations
Numerical and alphabetical suffixes
Abbreviations, easy
Abbreviations, simple
Abbreviations, automatic
Song lyrics/poems/Mad Libs/phrases
Mad Libs
Magic 8-ball
99 Bottles of Beer
The Name Game (a song)
The Old lady swallowed a fly
The Twelve Days of Christmas
Tokenize
Text between
Tokenize a string
Word break problem
Tokenize a string with escaping
Split a character string based on change of character
Sequences
Show ASCII table
De Bruijn sequences
Self-referential sequences
Generate lower case ASCII alphabet
| #Wee_Basic | Wee Basic | let string$=""
if string$=""
print 1 "The string is empty."
elseif string$<>""
print 1 "The string is not empty."
endif
end |
http://rosettacode.org/wiki/Empty_string | Empty string | Languages may have features for dealing specifically with empty strings
(those containing no characters).
Task
Demonstrate how to assign an empty string to a variable.
Demonstrate how to check that a string is empty.
Demonstrate how to check that a string is not empty.
Other tasks related to string operations:
Metrics
Array length
String length
Copy a string
Empty string (assignment)
Counting
Word frequency
Letter frequency
Jewels and stones
I before E except after C
Bioinformatics/base count
Count occurrences of a substring
Count how many vowels and consonants occur in a string
Remove/replace
XXXX redacted
Conjugate a Latin verb
Remove vowels from a string
String interpolation (included)
Strip block comments
Strip comments from a string
Strip a set of characters from a string
Strip whitespace from a string -- top and tail
Strip control codes and extended characters from a string
Anagrams/Derangements/shuffling
Word wheel
ABC problem
Sattolo cycle
Knuth shuffle
Ordered words
Superpermutation minimisation
Textonyms (using a phone text pad)
Anagrams
Anagrams/Deranged anagrams
Permutations/Derangements
Find/Search/Determine
ABC words
Odd words
Word ladder
Semordnilap
Word search
Wordiff (game)
String matching
Tea cup rim text
Alternade words
Changeable words
State name puzzle
String comparison
Unique characters
Unique characters in each string
Extract file extension
Levenshtein distance
Palindrome detection
Common list elements
Longest common suffix
Longest common prefix
Compare a list of strings
Longest common substring
Find common directory path
Words from neighbour ones
Change e letters to i in words
Non-continuous subsequences
Longest common subsequence
Longest palindromic substrings
Longest increasing subsequence
Words containing "the" substring
Sum of the digits of n is substring of n
Determine if a string is numeric
Determine if a string is collapsible
Determine if a string is squeezable
Determine if a string has all unique characters
Determine if a string has all the same characters
Longest substrings without repeating characters
Find words which contains all the vowels
Find words which contains most consonants
Find words which contains more than 3 vowels
Find words which first and last three letters are equals
Find words which odd letters are consonants and even letters are vowels or vice_versa
Formatting
Substring
Rep-string
Word wrap
String case
Align columns
Literals/String
Repeat a string
Brace expansion
Brace expansion using ranges
Reverse a string
Phrase reversals
Comma quibbling
Special characters
String concatenation
Substring/Top and tail
Commatizing numbers
Reverse words in a string
Suffixation of decimal numbers
Long literals, with continuations
Numerical and alphabetical suffixes
Abbreviations, easy
Abbreviations, simple
Abbreviations, automatic
Song lyrics/poems/Mad Libs/phrases
Mad Libs
Magic 8-ball
99 Bottles of Beer
The Name Game (a song)
The Old lady swallowed a fly
The Twelve Days of Christmas
Tokenize
Text between
Tokenize a string
Word break problem
Tokenize a string with escaping
Split a character string based on change of character
Sequences
Show ASCII table
De Bruijn sequences
Self-referential sequences
Generate lower case ASCII alphabet
| #Wren | Wren | var isEmpty = Fn.new { |s| s == "" }
var s = ""
var t = "0"
System.print("'s' is empty? %(isEmpty.call(s))")
System.print("'t' is empty? %(isEmpty.call(t))") |
http://rosettacode.org/wiki/Empty_program | Empty program | Task
Create the simplest possible program that is still considered "correct."
| #Seed7 | Seed7 | $ include "seed7_05.s7i";
const proc: main is noop; |
http://rosettacode.org/wiki/Empty_program | Empty program | Task
Create the simplest possible program that is still considered "correct."
| #Set_lang | Set lang | |
http://rosettacode.org/wiki/Empty_program | Empty program | Task
Create the simplest possible program that is still considered "correct."
| #Sidef | Sidef | |
http://rosettacode.org/wiki/Earliest_difference_between_prime_gaps | Earliest difference between prime gaps | When calculating prime numbers > 2, the difference between adjacent primes is always an even number. This difference, also referred to as the gap, varies in an random pattern; at least, no pattern has ever been discovered, and it is strongly conjectured that no pattern exists. However, it is also conjectured that between some two adjacent primes will be a gap corresponding to every positive even integer.
gap
minimal
starting
prime
ending
prime
2
3
5
4
7
11
6
23
29
8
89
97
10
139
149
12
199
211
14
113
127
16
1831
1847
18
523
541
20
887
907
22
1129
1151
24
1669
1693
26
2477
2503
28
2971
2999
30
4297
4327
This task involves locating the minimal primes corresponding to those gaps.
Though every gap value exists, they don't seem to come in any particular order. For example, this table shows the gaps and minimum starting value primes for 2 through 30:
For the purposes of this task, considering only primes greater than 2, consider prime gaps that differ by exactly two to be adjacent.
Task
For each order of magnitude m from 10¹ through 10⁶:
Find the first two sets of adjacent minimum prime gaps where the absolute value of the difference between the prime gap start values is greater than m.
E.G.
For an m of 10¹;
The start value of gap 2 is 3, the start value of gap 4 is 7, the difference is 7 - 3 or 4. 4 < 10¹ so keep going.
The start value of gap 4 is 7, the start value of gap 6 is 23, the difference is 23 - 7, or 16. 16 > 10¹ so this the earliest adjacent gap difference > 10¹.
Stretch goal
Do the same for 10⁷ and 10⁸ (and higher?) orders of magnitude
Note: the earliest value found for each order of magnitude may not be unique, in fact, is not unique; also, with the gaps in ascending order, the minimal starting values are not strictly ascending.
| #Java | Java | import java.util.HashMap;
import java.util.Map;
public class PrimeGaps {
private Map<Integer, Integer> gapStarts = new HashMap<>();
private int lastPrime;
private PrimeGenerator primeGenerator = new PrimeGenerator(1000, 500000);
public static void main(String[] args) {
final int limit = 100000000;
PrimeGaps pg = new PrimeGaps();
for (int pm = 10, gap1 = 2;;) {
int start1 = pg.findGapStart(gap1);
int gap2 = gap1 + 2;
int start2 = pg.findGapStart(gap2);
int diff = start2 > start1 ? start2 - start1 : start1 - start2;
if (diff > pm) {
System.out.printf(
"Earliest difference > %,d between adjacent prime gap starting primes:\n"
+ "Gap %,d starts at %,d, gap %,d starts at %,d, difference is %,d.\n\n",
pm, gap1, start1, gap2, start2, diff);
if (pm == limit)
break;
pm *= 10;
} else {
gap1 = gap2;
}
}
}
private int findGapStart(int gap) {
Integer start = gapStarts.get(gap);
if (start != null)
return start;
for (;;) {
int prev = lastPrime;
lastPrime = primeGenerator.nextPrime();
int diff = lastPrime - prev;
gapStarts.putIfAbsent(diff, prev);
if (diff == gap)
return prev;
}
}
} |
http://rosettacode.org/wiki/Earliest_difference_between_prime_gaps | Earliest difference between prime gaps | When calculating prime numbers > 2, the difference between adjacent primes is always an even number. This difference, also referred to as the gap, varies in an random pattern; at least, no pattern has ever been discovered, and it is strongly conjectured that no pattern exists. However, it is also conjectured that between some two adjacent primes will be a gap corresponding to every positive even integer.
gap
minimal
starting
prime
ending
prime
2
3
5
4
7
11
6
23
29
8
89
97
10
139
149
12
199
211
14
113
127
16
1831
1847
18
523
541
20
887
907
22
1129
1151
24
1669
1693
26
2477
2503
28
2971
2999
30
4297
4327
This task involves locating the minimal primes corresponding to those gaps.
Though every gap value exists, they don't seem to come in any particular order. For example, this table shows the gaps and minimum starting value primes for 2 through 30:
For the purposes of this task, considering only primes greater than 2, consider prime gaps that differ by exactly two to be adjacent.
Task
For each order of magnitude m from 10¹ through 10⁶:
Find the first two sets of adjacent minimum prime gaps where the absolute value of the difference between the prime gap start values is greater than m.
E.G.
For an m of 10¹;
The start value of gap 2 is 3, the start value of gap 4 is 7, the difference is 7 - 3 or 4. 4 < 10¹ so keep going.
The start value of gap 4 is 7, the start value of gap 6 is 23, the difference is 23 - 7, or 16. 16 > 10¹ so this the earliest adjacent gap difference > 10¹.
Stretch goal
Do the same for 10⁷ and 10⁸ (and higher?) orders of magnitude
Note: the earliest value found for each order of magnitude may not be unique, in fact, is not unique; also, with the gaps in ascending order, the minimal starting values are not strictly ascending.
| #Julia | Julia | using Formatting
using Primes
function primegaps(limit = 10^9)
c(n) = format(n, commas=true)
pri = primes(limit * 5)
gapstarts = Dict{Int, Int}()
for i in 2:length(pri)
get!(gapstarts, pri[i] - pri[i - 1], pri[i - 1])
end
pm, gap1 = 10, 2
while true
while !haskey(gapstarts, gap1)
gap1 += 2
end
start1 = gapstarts[gap1]
gap2 = gap1 + 2
if !haskey(gapstarts, gap2)
gap1 = gap2 + 2
continue
end
start2 = gapstarts[gap2]
if ((diff = abs(start2 - start1)) > pm)
println("Earliest difference > $(c(pm)) between adjacent prime gap starting primes:")
println("Gap $gap1 starts at $(c(start1)), gap $(c(gap2)) starts at $(c(start2)), difference is $(c(diff)).\n")
pm == limit && break
pm *= 10
else
gap1 = gap2
end
end
end
primegaps()
|
http://rosettacode.org/wiki/Element-wise_operations | Element-wise operations | This task is similar to:
Matrix multiplication
Matrix transposition
Task
Implement basic element-wise matrix-matrix and scalar-matrix operations, which can be referred to in other, higher-order tasks.
Implement:
addition
subtraction
multiplication
division
exponentiation
Extend the task if necessary to include additional basic operations, which should not require their own specialised task.
| #C | C | #include <math.h>
#define for_i for(i = 0; i < h; i++)
#define for_j for(j = 0; j < w; j++)
#define _M double**
#define OPM(name, _op_) \
void eop_##name(_M a, _M b, _M c, int w, int h){int i,j;\
for_i for_j c[i][j] = a[i][j] _op_ b[i][j];}
OPM(add, +);OPM(sub, -);OPM(mul, *);OPM(div, /);
#define OPS(name, res) \
void eop_s_##name(_M a, double s, _M b, int w, int h) {double x;int i,j;\
for_i for_j {x = a[i][j]; b[i][j] = res;}}
OPS(mul, x*s);OPS(div, x/s);OPS(add, x+s);OPS(sub, x-s);OPS(pow, pow(x, s)); |
http://rosettacode.org/wiki/Egyptian_division | Egyptian division | Egyptian division is a method of dividing integers using addition and
doubling that is similar to the algorithm of Ethiopian multiplication
Algorithm:
Given two numbers where the dividend is to be divided by the divisor:
Start the construction of a table of two columns: powers_of_2, and doublings; by a first row of a 1 (i.e. 2^0) in the first column and 1 times the divisor in the first row second column.
Create the second row with columns of 2 (i.e 2^1), and 2 * divisor in order.
Continue with successive i’th rows of 2^i and 2^i * divisor.
Stop adding rows, and keep only those rows, where 2^i * divisor is less than or equal to the dividend.
We now assemble two separate sums that both start as zero, called here answer and accumulator
Consider each row of the table, in the reverse order of its construction.
If the current value of the accumulator added to the doublings cell would be less than or equal to the dividend then add it to the accumulator, as well as adding the powers_of_2 cell value to the answer.
When the first row has been considered as above, then the integer division of dividend by divisor is given by answer.
(And the remainder is given by the absolute value of accumulator - dividend).
Example: 580 / 34
Table creation:
powers_of_2
doublings
1
34
2
68
4
136
8
272
16
544
Initialization of sums:
powers_of_2
doublings
answer
accumulator
1
34
2
68
4
136
8
272
16
544
0
0
Considering table rows, bottom-up:
When a row is considered it is shown crossed out if it is not accumulated, or bold if the row causes summations.
powers_of_2
doublings
answer
accumulator
1
34
2
68
4
136
8
272
16
544
16
544
powers_of_2
doublings
answer
accumulator
1
34
2
68
4
136
8
272
16
544
16
544
powers_of_2
doublings
answer
accumulator
1
34
2
68
4
136
16
544
8
272
16
544
powers_of_2
doublings
answer
accumulator
1
34
2
68
16
544
4
136
8
272
16
544
powers_of_2
doublings
answer
accumulator
1
34
17
578
2
68
4
136
8
272
16
544
Answer
So 580 divided by 34 using the Egyptian method is 17 remainder (578 - 580) or 2.
Task
The task is to create a function that does Egyptian division. The function should
closely follow the description above in using a list/array of powers of two, and
another of doublings.
Functions should be clear interpretations of the algorithm.
Use the function to divide 580 by 34 and show the answer here, on this page.
Related tasks
Egyptian fractions
References
Egyptian Number System
| #Arturo | Arturo | egyptianDiv: function [dividend, divisor][
ensure -> and? dividend >= 0
divisor > 0
if dividend < divisor -> return @[0, dividend]
powersOfTwo: new [1]
doublings: new @[divisor]
d: divisor
while [true][
d: 2 * d
if d > dividend -> break
'powersOfTwo ++ 2 * last powersOfTwo
'doublings ++ d
]
answer: 0
accumulator: 0
loop (dec size doublings)..0 'i [
if dividend >= accumulator + doublings\[i] [
accumulator: accumulator + doublings\[i]
answer: answer + powersOfTwo\[i]
if accumulator = dividend -> break
]
]
return @[answer, dividend - accumulator]
]
dividend: 580
divisor: 34
[quotient, remainder]: egyptianDiv dividend divisor
print [dividend "divided by" divisor "is" quotient "with remainder" remainder] |
http://rosettacode.org/wiki/Egyptian_fractions | Egyptian fractions | An Egyptian fraction is the sum of distinct unit fractions such as:
1
2
+
1
3
+
1
16
(
=
43
48
)
{\displaystyle {\tfrac {1}{2}}+{\tfrac {1}{3}}+{\tfrac {1}{16}}\,(={\tfrac {43}{48}})}
Each fraction in the expression has a numerator equal to 1 (unity) and a denominator that is a positive integer, and all the denominators are distinct (i.e., no repetitions).
Fibonacci's Greedy algorithm for Egyptian fractions expands the fraction
x
y
{\displaystyle {\tfrac {x}{y}}}
to be represented by repeatedly performing the replacement
x
y
=
1
⌈
y
/
x
⌉
+
(
−
y
)
mod
x
y
⌈
y
/
x
⌉
{\displaystyle {\frac {x}{y}}={\frac {1}{\lceil y/x\rceil }}+{\frac {(-y)\!\!\!\!\mod x}{y\lceil y/x\rceil }}}
(simplifying the 2nd term in this replacement as necessary, and where
⌈
x
⌉
{\displaystyle \lceil x\rceil }
is the ceiling function).
For this task, Proper and improper fractions must be able to be expressed.
Proper fractions are of the form
a
b
{\displaystyle {\tfrac {a}{b}}}
where
a
{\displaystyle a}
and
b
{\displaystyle b}
are positive integers, such that
a
<
b
{\displaystyle a<b}
, and
improper fractions are of the form
a
b
{\displaystyle {\tfrac {a}{b}}}
where
a
{\displaystyle a}
and
b
{\displaystyle b}
are positive integers, such that a ≥ b.
(See the REXX programming example to view one method of expressing the whole number part of an improper fraction.)
For improper fractions, the integer part of any improper fraction should be first isolated and shown preceding the Egyptian unit fractions, and be surrounded by square brackets [n].
Task requirements
show the Egyptian fractions for:
43
48
{\displaystyle {\tfrac {43}{48}}}
and
5
121
{\displaystyle {\tfrac {5}{121}}}
and
2014
59
{\displaystyle {\tfrac {2014}{59}}}
for all proper fractions,
a
b
{\displaystyle {\tfrac {a}{b}}}
where
a
{\displaystyle a}
and
b
{\displaystyle b}
are positive one-or two-digit (decimal) integers, find and show an Egyptian fraction that has:
the largest number of terms,
the largest denominator.
for all one-, two-, and three-digit integers, find and show (as above). {extra credit}
Also see
Wolfram MathWorld™ entry: Egyptian fraction
| #C | C | #include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
typedef int64_t integer;
struct Pair {
integer md;
int tc;
};
integer mod(integer x, integer y) {
return ((x % y) + y) % y;
}
integer gcd(integer a, integer b) {
if (0 == a) return b;
if (0 == b) return a;
if (a == b) return a;
if (a > b) return gcd(a - b, b);
return gcd(a, b - a);
}
void write0(bool show, char *str) {
if (show) {
printf(str);
}
}
void write1(bool show, char *format, integer a) {
if (show) {
printf(format, a);
}
}
void write2(bool show, char *format, integer a, integer b) {
if (show) {
printf(format, a, b);
}
}
struct Pair egyptian(integer x, integer y, bool show) {
struct Pair ret;
integer acc = 0;
bool first = true;
ret.tc = 0;
ret.md = 0;
write2(show, "Egyptian fraction for %lld/%lld: ", x, y);
while (x > 0) {
integer z = (y + x - 1) / x;
if (z == 1) {
acc++;
} else {
if (acc > 0) {
write1(show, "%lld + ", acc);
first = false;
acc = 0;
ret.tc++;
} else if (first) {
first = false;
} else {
write0(show, " + ");
}
if (z > ret.md) {
ret.md = z;
}
write1(show, "1/%lld", z);
ret.tc++;
}
x = mod(-y, x);
y = y * z;
}
if (acc > 0) {
write1(show, "%lld", acc);
ret.tc++;
}
write0(show, "\n");
return ret;
}
int main() {
struct Pair p;
integer nm = 0, dm = 0, dmn = 0, dmd = 0, den = 0;;
int tm, i, j;
egyptian(43, 48, true);
egyptian(5, 121, true); // final term cannot be represented correctly
egyptian(2014, 59, true);
tm = 0;
for (i = 1; i < 100; i++) {
for (j = 1; j < 100; j++) {
p = egyptian(i, j, false);
if (p.tc > tm) {
tm = p.tc;
nm = i;
dm = j;
}
if (p.md > den) {
den = p.md;
dmn = i;
dmd = j;
}
}
}
printf("Term max is %lld/%lld with %d terms.\n", nm, dm, tm); // term max is correct
printf("Denominator max is %lld/%lld\n", dmn, dmd); // denominator max is not correct
egyptian(dmn, dmd, true); // enough digits cannot be represented without bigint
return 0;
} |
http://rosettacode.org/wiki/Eertree | Eertree | An eertree is a data structure designed for efficient processing of certain palindrome tasks, for instance counting the number of sub-palindromes in an input string.
The data structure has commonalities to both tries and suffix trees.
See links below.
Task
Construct an eertree for the string "eertree", then output all sub-palindromes by traversing the tree.
See also
Wikipedia entry: trie.
Wikipedia entry: suffix tree
Cornell University Library, Computer Science, Data Structures and Algorithms ───► EERTREE: An Efficient Data Structure for Processing Palindromes in Strings.
| #Objeck | Objeck | use Collection.Generic;
class Eertree {
function : Main(args : String[]) ~ Nil {
tree := GetEertree("eertree");
Show(SubPalindromes(tree));
}
function : GetEertree(s : String) ~ Vector<Node> {
tree := Vector->New()<Node>;
tree->AddBack(Node->New(0, Nil, 1));
tree->AddBack(Node->New(-1, Nil, 1));
suffix := 1;
n : Int; k : Int;
for(i := 0; i < s->Size(); ++i;) {
c := s->Get(i);
done := false;
for (j := suffix; <>done; j := tree->Get(j)->GetSuffix();) {
k := tree->Get(j)->GetLength();
b := i - k - 1;
if (b >= 0 & s->Get(b) = c) {
n := j;
done := true;
};
};
skip := false;
if (tree->Get(n)->GetEdges()->Has(c)) {
suffix := tree->Get(n)->GetEdges()->Find(c)->Get();
skip := true;
};
if(<>skip) {
suffix := tree->Size();
tree->AddBack(Node->New(k + 2));
tree->Get(n)->GetEdges()->Insert(c, suffix);
if (tree->Get(suffix)->GetLength() = 1) {
tree->Get(suffix)->SetSuffix(0);
skip := true;
};
if(<>skip) {
done := false;
while (<>done) {
n := tree->Get(n)->GetSuffix();
b := i - tree->Get(n)->GetLength() - 1;
if (b >= 0 & s->Get(b) = c) {
done := true;
};
};
tree->Get(suffix)->SetSuffix(tree->Get(n)->GetEdges()->Find(c)->Get());
};
};
};
return tree;
}
function : SubPalindromes(tree : Vector<Node>) ~ Vector<String> {
s := Vector->New()<String>;
SubPalindromesChildren(0, "", tree, s);
keys := tree->Get(1)->GetEdges()->GetKeys()<CharHolder>;
each(k : keys) {
key := keys->Get(k);
str := key->Get()->ToString();
s->AddBack(str);
value := tree->Get(1)->GetEdges()->Find(key)->As(IntHolder)->Get();
SubPalindromesChildren(value, str, tree, s);
};
return s;
}
function : SubPalindromesChildren(n : Int, p : String, tree : Vector<Node>, s : Vector<String>) ~ Nil {
keys := tree->Get(n)->GetEdges()->GetKeys()<CharHolder>;
each(k : keys) {
key := keys->Get(k);
c := key->Get();
value := tree->Get(n)->GetEdges()->Find(key)->As(IntHolder)->Get();
str := ""; str += c; str += p; str += c;
s->AddBack(str);
SubPalindromesChildren(value, str, tree, s);
};
}
function : Show(result : Vector<String>) ~ Nil {
out := "[";
each(i : result) {
out += result->Get(i);
if(i + 1 < result->Size()) {
out += ", ";
};
};
out += "]";
out->PrintLine();
}
}
class Node {
@length : Int;
@edges : Map<CharHolder, IntHolder>;
@suffix : Int;
New(length : Int, edges : Map<CharHolder, IntHolder>, suffix : Int) {
@length := length;
@edges := edges <> Nil ? edges : Map->New()<CharHolder, IntHolder>;
@suffix := suffix;
}
New(length : Int) {
@length := length;
@edges := Map->New()<CharHolder, IntHolder>;
}
method : public : GetLength() ~ Int {
return @length;
}
method : public : GetSuffix() ~ Int {
return @suffix;
}
method : public : SetSuffix(suffix : Int) ~ Nil {
@suffix := suffix;
}
method : public : GetEdges() ~ Map<CharHolder, IntHolder> {
return @edges;
}
} |
http://rosettacode.org/wiki/Ethiopian_multiplication | Ethiopian multiplication | Ethiopian multiplication is a method of multiplying integers using only addition, doubling, and halving.
Method:
Take two numbers to be multiplied and write them down at the top of two columns.
In the left-hand column repeatedly halve the last number, discarding any remainders, and write the result below the last in the same column, until you write a value of 1.
In the right-hand column repeatedly double the last number and write the result below. stop when you add a result in the same row as where the left hand column shows 1.
Examine the table produced and discard any row where the value in the left column is even.
Sum the values in the right-hand column that remain to produce the result of multiplying the original two numbers together
For example: 17 × 34
17 34
Halving the first column:
17 34
8
4
2
1
Doubling the second column:
17 34
8 68
4 136
2 272
1 544
Strike-out rows whose first cell is even:
17 34
8 68
4 136
2 272
1 544
Sum the remaining numbers in the right-hand column:
17 34
8 --
4 ---
2 ---
1 544
====
578
So 17 multiplied by 34, by the Ethiopian method is 578.
Task
The task is to define three named functions/methods/procedures/subroutines:
one to halve an integer,
one to double an integer, and
one to state if an integer is even.
Use these functions to create a function that does Ethiopian multiplication.
References
Ethiopian multiplication explained (BBC Video clip)
A Night Of Numbers - Go Forth And Multiply (Video)
Russian Peasant Multiplication
Programming Praxis: Russian Peasant Multiplication
| #Python | Python | tutor = True
def halve(x):
return x // 2
def double(x):
return x * 2
def even(x):
return not x % 2
def ethiopian(multiplier, multiplicand):
if tutor:
print("Ethiopian multiplication of %i and %i" %
(multiplier, multiplicand))
result = 0
while multiplier >= 1:
if even(multiplier):
if tutor:
print("%4i %6i STRUCK" %
(multiplier, multiplicand))
else:
if tutor:
print("%4i %6i KEPT" %
(multiplier, multiplicand))
result += multiplicand
multiplier = halve(multiplier)
multiplicand = double(multiplicand)
if tutor:
print()
return result |
http://rosettacode.org/wiki/Elementary_cellular_automaton | Elementary cellular automaton | An elementary cellular automaton is a one-dimensional cellular automaton where there are two possible states (labeled 0 and 1) and the rule to determine the state of a cell in the next generation depends only on the current state of the cell and its two immediate neighbors. Those three values can be encoded with three bits.
The rules of evolution are then encoded with eight bits indicating the outcome of each of the eight possibilities 111, 110, 101, 100, 011, 010, 001 and 000 in this order. Thus for instance the rule 13 means that a state is updated to 1 only in the cases 011, 010 and 000, since 13 in binary is 0b00001101.
Task
Create a subroutine, program or function that allows to create and visualize the evolution of any of the 256 possible elementary cellular automaton of arbitrary space length and for any given initial state. You can demonstrate your solution with any automaton of your choice.
The space state should wrap: this means that the left-most cell should be considered as the right neighbor of the right-most cell, and reciprocally.
This task is basically a generalization of one-dimensional cellular automata.
See also
Cellular automata (natureofcode.com)
| #D | D | import std.stdio, std.string, std.conv, std.range, std.algorithm, std.typecons;
enum mod = (in int n, in int m) pure nothrow @safe @nogc => ((n % m) + m) % m;
struct ECAwrap {
public string front;
public enum bool empty = false;
private immutable const(char)[string] next;
this(in string cells_, in uint rule) pure @safe {
this.front = cells_;
immutable ruleBits = "%08b".format(rule).retro.text;
next = 8.iota.map!(n => tuple("%03b".format(n), char(ruleBits[n]))).assocArray;
}
void popFront() pure @safe {
alias c = front;
c = iota(c.length)
.map!(i => next[[c[(i - 1).mod($)], c[i], c[(i + 1) % $]]])
.text;
}
}
void main() @safe {
enum nLines = 50;
immutable string start = "0000000001000000000";
immutable uint[] rules = [90, 30, 122];
writeln("Rules: ", rules);
auto ecas = rules.map!(rule => ECAwrap(start, rule)).array;
foreach (immutable i; 0 .. nLines) {
writefln("%2d: %-(%s %)", i, ecas.map!(eca => eca.front.tr("01", ".#")));
foreach (ref eca; ecas)
eca.popFront;
}
} |
http://rosettacode.org/wiki/Factorial | Factorial | Definitions
The factorial of 0 (zero) is defined as being 1 (unity).
The Factorial Function of a positive integer, n, is defined as the product of the sequence:
n, n-1, n-2, ... 1
Task
Write a function to return the factorial of a number.
Solutions can be iterative or recursive.
Support for trapping negative n errors is optional.
Related task
Primorial numbers
| #Tailspin | Tailspin |
templates factorial
when <0..> do
@: 1;
1..$ -> @: $@ * $;
$@ !
end factorial
|
http://rosettacode.org/wiki/Even_or_odd | Even or odd | Task
Test whether an integer is even or odd.
There is more than one way to solve this task:
Use the even and odd predicates, if the language provides them.
Check the least significant digit. With binary integers, i bitwise-and 1 equals 0 iff i is even, or equals 1 iff i is odd.
Divide i by 2. The remainder equals 0 iff i is even. The remainder equals +1 or -1 iff i is odd.
Use modular congruences:
i ≡ 0 (mod 2) iff i is even.
i ≡ 1 (mod 2) iff i is odd.
| #UNIX_Shell | UNIX Shell | iseven() {
[[ $(($1%2)) -eq 0 ]] && return 0
return 1
} |
http://rosettacode.org/wiki/Even_or_odd | Even or odd | Task
Test whether an integer is even or odd.
There is more than one way to solve this task:
Use the even and odd predicates, if the language provides them.
Check the least significant digit. With binary integers, i bitwise-and 1 equals 0 iff i is even, or equals 1 iff i is odd.
Divide i by 2. The remainder equals 0 iff i is even. The remainder equals +1 or -1 iff i is odd.
Use modular congruences:
i ≡ 0 (mod 2) iff i is even.
i ≡ 1 (mod 2) iff i is odd.
| #Ursa | Ursa | decl int input
set input (in int console)
if (= (mod input 2) 1)
out "odd" endl console
else
out "even" endl console
end if |
http://rosettacode.org/wiki/Echo_server | Echo server | Create a network service that sits on TCP port 12321, which accepts connections on that port, and which echoes complete lines (using a carriage-return/line-feed sequence as line separator) back to clients. No error handling is required. For the purposes of testing, it is only necessary to support connections from localhost (127.0.0.1 or perhaps ::1). Logging of connection information to standard output is recommended.
The implementation must be able to handle simultaneous connections from multiple clients. A multi-threaded or multi-process solution may be used. Each connection must be able to echo more than a single line.
The implementation must not stop responding to other clients if one client sends a partial line or stops reading responses.
| #F.23 | F# | open System.IO
open System.Net
open System.Net.Sockets
let service (client:TcpClient) =
use stream = client.GetStream()
use out = new StreamWriter(stream, AutoFlush = true)
use inp = new StreamReader(stream)
while not inp.EndOfStream do
match inp.ReadLine() with
| line -> printfn "< %s" line
out.WriteLine(line)
printfn "closed %A" client.Client.RemoteEndPoint
client.Close |> ignore
let EchoService =
let socket = new TcpListener(IPAddress.Loopback, 12321)
do socket.Start()
printfn "echo service listening on %A" socket.Server.LocalEndPoint
while true do
let client = socket.AcceptTcpClient()
printfn "connect from %A" client.Client.RemoteEndPoint
let job = async {
use c = client in try service client with _ -> () }
Async.Start job
[<EntryPoint>]
let main _ =
EchoService
0 |
http://rosettacode.org/wiki/Elementary_cellular_automaton/Infinite_length | Elementary cellular automaton/Infinite length | The purpose of this task is to create a version of an Elementary cellular automaton whose number of cells is only limited by the memory size of the computer.
To be precise, consider the state of the automaton to be made of an infinite number of cells, but with a bounded support. In other words, to describe the state of the automaton, you need a finite number of adjacent cells, along with their individual state, and you then consider that the individual state of each of all other cells is the negation of the closest individual cell among the previously defined finite number of cells.
Examples:
1 -> ..., 0, 0, 1, 0, 0, ...
0, 1 -> ..., 1, 1, 0, 1, 0, 0, ...
1, 0, 1 -> ..., 0, 0, 1, 0, 1, 0, 0, ...
More complex methods can be imagined, provided it is possible to somehow encode the infinite sections. But for this task we will stick to this simple version.
| #zkl | zkl | nLines,flipCell := 25, fcn(c){ (c=="1") and "0" or "1" };
foreach rule in (T(90,30)){
println("\nRule: ", rule);
ruleBits:="%08.2B".fmt(rule); // eg 90-->"01011010"
neighs2next:=(8).pump(Dictionary(),
'wrap(n){ T("%03.2B".fmt(n), ruleBits.reverse()[n]) });
C:="1"; // C is "1"s and "0"s, I'll auto cast to Int as needed
foreach i in (nLines){
println("%2d: %s%s".fmt(i," "*(nLines - i), C.translate("01",".#")));
C=String(flipCell(C[0])*2, C, flipCell(C[-1])*2);
C=[1..C.len()-2].pump(String,'wrap(n){ neighs2next[C[n-1,3]] });
}
} |
http://rosettacode.org/wiki/Empty_string | Empty string | Languages may have features for dealing specifically with empty strings
(those containing no characters).
Task
Demonstrate how to assign an empty string to a variable.
Demonstrate how to check that a string is empty.
Demonstrate how to check that a string is not empty.
Other tasks related to string operations:
Metrics
Array length
String length
Copy a string
Empty string (assignment)
Counting
Word frequency
Letter frequency
Jewels and stones
I before E except after C
Bioinformatics/base count
Count occurrences of a substring
Count how many vowels and consonants occur in a string
Remove/replace
XXXX redacted
Conjugate a Latin verb
Remove vowels from a string
String interpolation (included)
Strip block comments
Strip comments from a string
Strip a set of characters from a string
Strip whitespace from a string -- top and tail
Strip control codes and extended characters from a string
Anagrams/Derangements/shuffling
Word wheel
ABC problem
Sattolo cycle
Knuth shuffle
Ordered words
Superpermutation minimisation
Textonyms (using a phone text pad)
Anagrams
Anagrams/Deranged anagrams
Permutations/Derangements
Find/Search/Determine
ABC words
Odd words
Word ladder
Semordnilap
Word search
Wordiff (game)
String matching
Tea cup rim text
Alternade words
Changeable words
State name puzzle
String comparison
Unique characters
Unique characters in each string
Extract file extension
Levenshtein distance
Palindrome detection
Common list elements
Longest common suffix
Longest common prefix
Compare a list of strings
Longest common substring
Find common directory path
Words from neighbour ones
Change e letters to i in words
Non-continuous subsequences
Longest common subsequence
Longest palindromic substrings
Longest increasing subsequence
Words containing "the" substring
Sum of the digits of n is substring of n
Determine if a string is numeric
Determine if a string is collapsible
Determine if a string is squeezable
Determine if a string has all unique characters
Determine if a string has all the same characters
Longest substrings without repeating characters
Find words which contains all the vowels
Find words which contains most consonants
Find words which contains more than 3 vowels
Find words which first and last three letters are equals
Find words which odd letters are consonants and even letters are vowels or vice_versa
Formatting
Substring
Rep-string
Word wrap
String case
Align columns
Literals/String
Repeat a string
Brace expansion
Brace expansion using ranges
Reverse a string
Phrase reversals
Comma quibbling
Special characters
String concatenation
Substring/Top and tail
Commatizing numbers
Reverse words in a string
Suffixation of decimal numbers
Long literals, with continuations
Numerical and alphabetical suffixes
Abbreviations, easy
Abbreviations, simple
Abbreviations, automatic
Song lyrics/poems/Mad Libs/phrases
Mad Libs
Magic 8-ball
99 Bottles of Beer
The Name Game (a song)
The Old lady swallowed a fly
The Twelve Days of Christmas
Tokenize
Text between
Tokenize a string
Word break problem
Tokenize a string with escaping
Split a character string based on change of character
Sequences
Show ASCII table
De Bruijn sequences
Self-referential sequences
Generate lower case ASCII alphabet
| #X86-64_Assembly | X86-64 Assembly |
option casemap:none
printf proto :qword, :VARARG
exit proto :dword
.data
e_str db 1 dup (0)
.code
main proc
xor rcx, rcx
lea rax, e_str
cmp byte ptr [rax+rcx],0 ;; Is e_str[0] equal to 0?
je _isempty ;; Yes so goto isEmpty
jne _notempty ;; No, got notEmpty
jmp _exit ;; Neither condition is met, so exit.
_isempty:
invoke printf, CSTR("e_str is empty",10)
lea rax, e_str
mov byte ptr [rax+0], 's' ;; Copy a char into e_str[0]
jmp main ;; Test again..
_notempty:
invoke printf, CSTR("e_str is NOT empty",10)
;; Fall though to exit here..
_exit:
xor rsi, rsi
call exit
ret
main endp
end
|
http://rosettacode.org/wiki/Empty_string | Empty string | Languages may have features for dealing specifically with empty strings
(those containing no characters).
Task
Demonstrate how to assign an empty string to a variable.
Demonstrate how to check that a string is empty.
Demonstrate how to check that a string is not empty.
Other tasks related to string operations:
Metrics
Array length
String length
Copy a string
Empty string (assignment)
Counting
Word frequency
Letter frequency
Jewels and stones
I before E except after C
Bioinformatics/base count
Count occurrences of a substring
Count how many vowels and consonants occur in a string
Remove/replace
XXXX redacted
Conjugate a Latin verb
Remove vowels from a string
String interpolation (included)
Strip block comments
Strip comments from a string
Strip a set of characters from a string
Strip whitespace from a string -- top and tail
Strip control codes and extended characters from a string
Anagrams/Derangements/shuffling
Word wheel
ABC problem
Sattolo cycle
Knuth shuffle
Ordered words
Superpermutation minimisation
Textonyms (using a phone text pad)
Anagrams
Anagrams/Deranged anagrams
Permutations/Derangements
Find/Search/Determine
ABC words
Odd words
Word ladder
Semordnilap
Word search
Wordiff (game)
String matching
Tea cup rim text
Alternade words
Changeable words
State name puzzle
String comparison
Unique characters
Unique characters in each string
Extract file extension
Levenshtein distance
Palindrome detection
Common list elements
Longest common suffix
Longest common prefix
Compare a list of strings
Longest common substring
Find common directory path
Words from neighbour ones
Change e letters to i in words
Non-continuous subsequences
Longest common subsequence
Longest palindromic substrings
Longest increasing subsequence
Words containing "the" substring
Sum of the digits of n is substring of n
Determine if a string is numeric
Determine if a string is collapsible
Determine if a string is squeezable
Determine if a string has all unique characters
Determine if a string has all the same characters
Longest substrings without repeating characters
Find words which contains all the vowels
Find words which contains most consonants
Find words which contains more than 3 vowels
Find words which first and last three letters are equals
Find words which odd letters are consonants and even letters are vowels or vice_versa
Formatting
Substring
Rep-string
Word wrap
String case
Align columns
Literals/String
Repeat a string
Brace expansion
Brace expansion using ranges
Reverse a string
Phrase reversals
Comma quibbling
Special characters
String concatenation
Substring/Top and tail
Commatizing numbers
Reverse words in a string
Suffixation of decimal numbers
Long literals, with continuations
Numerical and alphabetical suffixes
Abbreviations, easy
Abbreviations, simple
Abbreviations, automatic
Song lyrics/poems/Mad Libs/phrases
Mad Libs
Magic 8-ball
99 Bottles of Beer
The Name Game (a song)
The Old lady swallowed a fly
The Twelve Days of Christmas
Tokenize
Text between
Tokenize a string
Word break problem
Tokenize a string with escaping
Split a character string based on change of character
Sequences
Show ASCII table
De Bruijn sequences
Self-referential sequences
Generate lower case ASCII alphabet
| #XLISP | XLISP | [1] (define my-empty-string "") ;; assign an empty string to a variable
MY-EMPTY-STRING
[2] (string-null? my-empty-string)
#T
[3] (string-null? "A non-empty string")
() |
http://rosettacode.org/wiki/Empty_program | Empty program | Task
Create the simplest possible program that is still considered "correct."
| #SimpleCode | SimpleCode |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.