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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).
| #jq | jq |
# jq optimizes the recursive call of _gcd in the following:
def gcd(a;b):
def _gcd:
if .[1] != 0 then [.[1], .[0] % .[1]] | _gcd else .[0] end;
[a,b] | _gcd ;
def lpad($len): tostring | ($len - length) as $l | (" " * $l)[:$l] + .;
|
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).
| #Julia | Julia | using Primes
function ekgsequence(n, limit)
ekg::Array{Int,1} = [1, n]
while length(ekg) < limit
for i in 2:2<<18
if all(j -> j != i, ekg) && gcd(ekg[end], i) > 1
push!(ekg, i)
break
end
end
end
ekg
end
function convergeat(n, m, max = 100)
ekgn = ekgsequence(n, max)
ekgm = ekgsequence(m, max)
for i in 3:max
if ekgn[i] == ekgm[i] && sum(ekgn[1:i+1]) == sum(ekgm[1:i+1])
return i
end
end
warn("no converge in $max terms")
end
[println(rpad("EKG($i): ", 9), join(ekgsequence(i, 30), " ")) for i in [2, 5, 7, 9, 10]]
println("EKGs of 5 & 7 converge at term ", convergeat(5, 7))
|
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
| #Scheme | Scheme | (define empty-string "")
(define (string-null? s) (string=? "" s))
(define (string-not-null? s) (string<? "" s)) |
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
| #Seed7 | Seed7 | # assign empty string to a variable
s := ""
# check that string is empty
s = ""
# check that string is not empty
s <> "" |
http://rosettacode.org/wiki/Empty_program | Empty program | Task
Create the simplest possible program that is still considered "correct."
| #PL.2FSQL | PL/SQL | BEGIN
NULL;
END; |
http://rosettacode.org/wiki/Empty_program | Empty program | Task
Create the simplest possible program that is still considered "correct."
| #Plain_English | Plain English | To run:
Start up.
Shut down. |
http://rosettacode.org/wiki/Empty_program | Empty program | Task
Create the simplest possible program that is still considered "correct."
| #Plain_TeX | Plain TeX | \bye |
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
| #Phix | Phix | function emHalf(integer n)
return floor(n/2)
end function
function emDouble(integer n)
return n*2
end function
function emIsEven(integer n)
return (remainder(n,2)=0)
end function
function emMultiply(integer a, integer b)
integer sum = 0
while a!=0 do
if not emIsEven(a) then sum += b end if
a = emHalf(a)
b = emDouble(b)
end while
return sum
end function
printf(1,"emMultiply(%d,%d) = %d\n",{17,34,emMultiply(17,34)})
|
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
| #Sisal | Sisal | define main
function main(x : integer returns integer)
for a in 1, x
returns
value of product a
end for
end function |
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.
| #S-BASIC | S-BASIC |
rem - return true (-1) if even, otherwise false (0)
function even(i = integer) = integer
var one = integer rem - both operands must be variables
one = 1
end = ((i and one) = 0)
rem - exercise the function
var i = integer
for i = 1 to 10 step 3
print i; " is ";
if even(i) then
print "even"
else
print "odd"
next
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.
| #Scala | Scala | def isEven( v:Int ) : Boolean = v % 2 == 0
def isOdd( v:Int ) : Boolean = v % 2 != 0 |
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.
| #BaCon | BaCon | OPEN "localhost:12321" FOR SERVER AS echo
WHILE TRUE
fd = ACCEPT(echo)
PRINT "Incoming connection from: ", GETPEER$(fd)
RECEIVE data$ FROM fd
SEND data$ & CR$ & NL$ TO fd
CLOSE SERVER fd
WEND |
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.
| #C.2B.2B | C++ |
#include <iostream>
#include <iomanip>
#include <string>
class oo {
public:
void evolve( int l, int rule ) {
std::string cells = "O";
std::cout << " Rule #" << rule << ":\n";
for( int x = 0; x < l; x++ ) {
addNoCells( cells );
std::cout << std::setw( 40 + ( static_cast<int>( cells.length() ) >> 1 ) ) << cells << "\n";
step( cells, rule );
}
}
private:
void step( std::string& cells, int rule ) {
int bin;
std::string newCells;
for( size_t i = 0; i < cells.length() - 2; i++ ) {
bin = 0;
for( size_t n = i, b = 2; n < i + 3; n++, b >>= 1 ) {
bin += ( ( cells[n] == 'O' ? 1 : 0 ) << b );
}
newCells.append( 1, rule & ( 1 << bin ) ? 'O' : '.' );
}
cells = newCells;
}
void addNoCells( std::string& s ) {
char l = s.at( 0 ) == 'O' ? '.' : 'O',
r = s.at( s.length() - 1 ) == 'O' ? '.' : 'O';
s = l + s + r;
s = l + s + r;
}
};
int main( int argc, char* argv[] ) {
oo o;
o.evolve( 35, 90 );
std::cout << "\n";
return 0;
}
|
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).
| #Kotlin | Kotlin | // Version 1.2.60
fun gcd(a: Int, b: Int): Int {
var aa = a
var bb = b
while (aa != bb) {
if (aa > bb)
aa -= bb
else
bb -= aa
}
return aa
}
const val LIMIT = 100
fun main(args: Array<String>) {
val starts = listOf(2, 5, 7, 9, 10)
val ekg = Array(5) { IntArray(LIMIT) }
for ((s, start) in starts.withIndex()) {
ekg[s][0] = 1
ekg[s][1] = start
for (n in 2 until 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].slice(0 until n).contains(i) &&
gcd(ekg[s][n - 1], i) > 1) {
ekg[s][n] = i
break
}
i++
}
}
System.out.printf("EKG(%2d): %s\n", start, ekg[s].slice(0 until 30))
}
// now compare EKG5 and EKG7 for convergence
for (i in 2 until LIMIT) {
if (ekg[1][i] == ekg[2][i] &&
ekg[1].slice(0 until i).sorted() == ekg[2].slice(0 until i).sorted()) {
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/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
| #Self | Self |
"Put an empty string in a slot called 'str'"
str: ''.
"Check that string is empty"
str isEmpty.
"Check that string is not empty"
str isEmpty not. |
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
| #SenseTalk | SenseTalk |
set emptyString to ""
put emptyString
put emptyString is empty
put emptyString is not empty
|
http://rosettacode.org/wiki/Empty_program | Empty program | Task
Create the simplest possible program that is still considered "correct."
| #Pony | Pony | actor Main new create(e: Env) => "" |
http://rosettacode.org/wiki/Empty_program | Empty program | Task
Create the simplest possible program that is still considered "correct."
| #Pop11 | Pop11 | ;;; This is a valid Pop11 program that does absolutely nothing. |
http://rosettacode.org/wiki/Empty_program | Empty program | Task
Create the simplest possible program that is still considered "correct."
| #PostScript | PostScript | %!PS |
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
| #PHP | PHP | <?php
function halve($x)
{
return floor($x/2);
}
function double($x)
{
return $x*2;
}
function iseven($x)
{
return !($x & 0x1);
}
function ethiopicmult($plier, $plicand, $tutor)
{
if ($tutor) echo "ethiopic multiplication of $plier and $plicand\n";
$r = 0;
while($plier >= 1) {
if ( !iseven($plier) ) $r += $plicand;
if ($tutor)
echo "$plier, $plicand ", (iseven($plier) ? "struck" : "kept"), "\n";
$plier = halve($plier);
$plicand = double($plicand);
}
return $r;
}
echo ethiopicmult(17, 34, true), "\n";
?> |
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
| #Slate | Slate | n@(Integer traits) factorial
"The standard recursive definition."
[
n isNegative ifTrue: [error: 'Negative inputs to factorial are invalid.'].
n <= 1
ifTrue: [1]
ifFalse: [n * ((n - 1) 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.
| #Scheme | Scheme | > (even? 5)
#f
> (even? 42)
#t
> (odd? 5)
#t
> (odd? 42)
#f |
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.
| #Seed7 | Seed7 | odd(aNumber) |
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.
| #BBC_BASIC | BBC BASIC | INSTALL @lib$+"SOCKLIB"
PROC_initsockets
maxSess% = 8
DIM sock%(maxSess%-1), rcvd$(maxSess%-1), Buffer% 255
ON ERROR PRINT REPORT$ : PROC_exitsockets : END
ON CLOSE PROC_exitsockets : QUIT
crlf$ = CHR$13 + CHR$10
port$ = "12321"
host$ = FN_gethostname
PRINT "Host name is " host$
listen% = FN_tcplisten(host$, port$)
PRINT "Listening on port ";port$
REPEAT
socket% = FN_check_connection(listen%)
IF socket% THEN
FOR i% = 0 TO maxSess%-1
IF sock%(i%) = 0 THEN
sock%(i%) = socket%
rcvd$(i%) = ""
PRINT "Connection on socket "; sock%(i%) " opened"
EXIT FOR
ENDIF
NEXT i%
listen% = FN_tcplisten(host$, port$)
ENDIF
FOR i% = 0 TO maxSess%-1
IF sock%(i%) THEN
res% = FN_readsocket(sock%(i%), Buffer%, 256)
IF res% >= 0 THEN
Buffer%?res% = 0
rcvd$(i%) += $$Buffer%
crlf% = INSTR(rcvd$(i%), crlf$)
IF crlf% THEN
echo$ = LEFT$(rcvd$(i%), crlf%-1)
res% = FN_writelinesocket(sock%(i%), echo$)
rcvd$(i%) = MID$(rcvd$(i%), crlf%+2)
ENDIF
ELSE
PROC_closesocket(sock%(i%))
PRINT "Connection on socket " ; sock%(i%) " closed"
sock%(i%) = 0
ENDIF
ENDIF
NEXT i%
WAIT 0
UNTIL FALSE
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.
| #D | D | import std.stdio, std.array, std.range, std.typecons, std.string, std.conv,
std.algorithm;
alias R = replicate;
void main() {
enum nLines = 25;
enum notCell = (in char c) pure => (c == '1') ? "0" : "1";
foreach (immutable rule; [90, 30]) {
writeln("\nRule: ", rule);
immutable ruleBits = "%08b".format(rule).retro.text;
const neighs2next = 8.iota
.map!(n => tuple("%03b".format(n), [ruleBits[n]]))
.assocArray;
string C = "1";
foreach (immutable i; 0 .. nLines) {
writefln("%2d: %s%s", i, " ".R(nLines - i), C.tr("01", ".#"));
C = notCell(C[0]).R(2) ~ C ~ notCell(C[$ - 1]).R(2);
C = iota(1, C.length - 1)
.map!(i => neighs2next[C[i - 1 .. i + 2]])
.join;
}
}
} |
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.
| #Elixir | Elixir |
defmodule Elementary_cellular_automaton do
def infinite(cell, rule, times) do
each(cell, rule_pattern(rule), times)
end
defp each(_, _, 0), do: :ok
defp each(cells, rules, times) do
IO.write String.duplicate(" ", times)
IO.puts String.replace(cells, "0", ".") |> String.replace("1", "#")
c = not_cell(String.first(cells)) <> cells <> not_cell(String.last(cells))
next_cells = Enum.map_join(0..String.length(cells)+1, fn i ->
Map.get(rules, String.slice(c, i, 3))
end)
each(next_cells, rules, times-1)
end
defp not_cell("0"), do: "11"
defp not_cell("1"), do: "00"
defp rule_pattern(rule) do
list = Integer.to_string(rule, 2) |> String.pad_leading(8, "0")
|> String.codepoints |> Enum.reverse
Enum.map(0..7, fn i -> Integer.to_string(i, 2) |> String.pad_leading(3, "0") end)
|> Enum.zip(list) |> Map.new
end
end
Enum.each([18, 30], fn rule ->
IO.puts "\nRule : #{rule}"
Elementary_cellular_automaton.infinite("1", rule, 25)
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).
| #Mathematica.2FWolfram_Language | Mathematica/Wolfram Language | ClearAll[NextInSequence, EKGSequence]
NextInSequence[seq_List] := Module[{last, new = 1, holes, max, sel, found, i},
last = Last[seq];
max = Max[seq];
holes = Complement[Range[max], seq];
sel = SelectFirst[holes, Not[CoprimeQ[last, #]] &];
If[MissingQ[sel],
i = max;
found = False;
While[! found,
i++;
If[Not[CoprimeQ[last, i]],
found = True
]
];
Append[seq, i]
,
Append[seq, sel]
]
]
EKGSequence[start_Integer, n_] := Nest[NextInSequence, {1, start}, n - 2]
Table[EKGSequence[s, 10], {s, {2, 5, 7, 9, 10}}] // Grid
s = Reverse[Transpose[{EKGSequence[5, 1000], EKGSequence[7, 1000]}]];
len = LengthWhile[s, Apply[Equal]];
s //= Reverse[Drop[#, len]] &;
Length[s] + 1 |
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).
| #Nim | Nim | import algorithm, math, sets, strformat, strutils
#---------------------------------------------------------------------------------------------------
iterator ekg(n, limit: Positive): (int, int) =
var values: HashSet[int]
doAssert n >= 2
yield (1, 1)
yield (2, n)
values.incl(n)
var i = 3
var prev = n
while i <= limit:
var val = 2
while true:
if val notin values and gcd(val, prev) != 1:
values.incl(val)
yield (i, val)
prev = val
break
inc val
inc i
#---------------------------------------------------------------------------------------------------
for n in [2, 5, 7, 9, 10]:
var result: array[1..10, int]
for i, val in ekg(n, 10): result[i] = val
let title = fmt"EKG({n}):"
echo fmt"{title:8} {result.join("", "")}"
var ekg5, ekg7: array[1..100, int]
for i, val in ekg(5, 100): ekg5[i] = val
for i, val in ekg(7, 100): ekg7[i] = val
var convIndex = 0
for i in 2..100:
if ekg5[i] == ekg7[i] and sorted(ekg5[1..<i]) == sorted(ekg7[1..<i]):
convIndex = i
break
if convIndex > 0:
echo fmt"EKG(5) and EKG(7) converge at index {convIndex}."
else:
echo "No convergence found in the first {convIndex} 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
| #Sidef | Sidef | var s = "";
var s = String.new; |
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
| #Smalltalk | Smalltalk | "Assign empty string to a variable"
str := ''.
"Check that string is empty"
str isEmpty.
"Check that string is not empty"
str isEmpty not.
"alternatives:"
str notEmpty
str size = 0
str = '' |
http://rosettacode.org/wiki/Empty_program | Empty program | Task
Create the simplest possible program that is still considered "correct."
| #PowerShell | PowerShell |
&{}
|
http://rosettacode.org/wiki/Empty_program | Empty program | Task
Create the simplest possible program that is still considered "correct."
| #Processing | Processing | |
http://rosettacode.org/wiki/Empty_program | Empty program | Task
Create the simplest possible program that is still considered "correct."
| #ProDOS | ProDOS | IGNORELINE |
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
| #Picat | Picat | ethiopian(Multiplier, Multiplicand) = ethiopian(Multiplier, Multiplicand,false).
ethiopian(Multiplier, Multiplicand,Tutor) = Result =>
if Tutor then
printf("\n%d * %d:\n",Multiplier, Multiplicand)
end,
Result1 = 0,
while (Multiplier >= 1)
OldResult = Result1,
if not even(Multiplier) then
Result1 := Result1 + Multiplicand
end,
if Tutor then
printf("%6d % 8s\n",Multiplier,cond(OldResult=Result1,"--",Multiplicand.to_string()))
end,
Multiplier := halve(Multiplier),
Multiplicand := double(Multiplicand)
end,
if Tutor then
println(" ======="),
printf(" %8s\n",Result1.to_string()),
nl
end,
Result = Result1. |
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
| #Smalltalk | Smalltalk | Number extend [
my_factorial [
(self < 2)
ifTrue: [ ^1 ]
ifFalse: [
^ (2 to: self) fold: [ :a :b | a * b ]
]
]
].
7 factorial printNl.
7 my_factorial printNl. |
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.
| #SenseTalk | SenseTalk |
set num to random of 100 -- start with a random number from 1 to 100
// use the 'is a' operator to test the value
if num is an odd number then put num & " is odd"
// see if num is divisible by 2
if num is divisible by 2 then put num & " is even (is divisible by 2)"
// check to see if the remainder is 0 when dividing by 2
if num rem 2 is 0 then put num & " is even (zero remainder)"
|
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.
| #SequenceL | SequenceL | even(x) := x mod 2 = 0;
odd(x) := x mod 2 = 1; |
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.
| #C | C | #include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netdb.h>
#include <unistd.h>
#include <sys/wait.h>
#include <signal.h>
#define MAX_ENQUEUED 20
#define BUF_LEN 256
#define PORT_STR "12321"
/* ------------------------------------------------------------ */
/* How to clean up after dead child processes */
/* ------------------------------------------------------------ */
void wait_for_zombie(int s)
{
while(waitpid(-1, NULL, WNOHANG) > 0) ;
}
/* ------------------------------------------------------------ */
/* Core of implementation of a child process */
/* ------------------------------------------------------------ */
void echo_lines(int csock)
{
char buf[BUF_LEN];
int r;
while( (r = read(csock, buf, BUF_LEN)) > 0 ) {
(void)write(csock, buf, r);
}
exit(EXIT_SUCCESS);
}
/* ------------------------------------------------------------ */
/* Core of implementation of the parent process */
/* ------------------------------------------------------------ */
void take_connections_forever(int ssock)
{
for(;;) {
struct sockaddr addr;
socklen_t addr_size = sizeof(addr);
int csock;
/* Block until we take one connection to the server socket */
csock = accept(ssock, &addr, &addr_size);
/* If it was a successful connection, spawn a worker process to service it */
if ( csock == -1 ) {
perror("accept");
} else if ( fork() == 0 ) {
close(ssock);
echo_lines(csock);
} else {
close(csock);
}
}
}
/* ------------------------------------------------------------ */
/* The server process's one-off setup code */
/* ------------------------------------------------------------ */
int main()
{
struct addrinfo hints, *res;
struct sigaction sa;
int sock;
/* Look up the address to bind to */
memset(&hints, 0, sizeof(struct addrinfo));
hints.ai_family = AF_UNSPEC;
hints.ai_socktype = SOCK_STREAM;
hints.ai_flags = AI_PASSIVE;
if ( getaddrinfo(NULL, PORT_STR, &hints, &res) != 0 ) {
perror("getaddrinfo");
exit(EXIT_FAILURE);
}
/* Make a socket */
if ( (sock = socket(res->ai_family, res->ai_socktype, res->ai_protocol)) == -1 ) {
perror("socket");
exit(EXIT_FAILURE);
}
/* Arrange to clean up child processes (the workers) */
sa.sa_handler = wait_for_zombie;
sigemptyset(&sa.sa_mask);
sa.sa_flags = SA_RESTART;
if ( sigaction(SIGCHLD, &sa, NULL) == -1 ) {
perror("sigaction");
exit(EXIT_FAILURE);
}
/* Associate the socket with its address */
if ( bind(sock, res->ai_addr, res->ai_addrlen) != 0 ) {
perror("bind");
exit(EXIT_FAILURE);
}
freeaddrinfo(res);
/* State that we've opened a server socket and are listening for connections */
if ( listen(sock, MAX_ENQUEUED) != 0 ) {
perror("listen");
exit(EXIT_FAILURE);
}
/* Serve the listening socket until killed */
take_connections_forever(sock);
return EXIT_SUCCESS;
} |
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.
| #Go | Go | package main
import (
"fmt"
"strings"
)
func btoi(b bool) int {
if b {
return 1
}
return 0
}
func evolve(l, rule int) {
fmt.Printf(" Rule #%d:\n", rule)
cells := "O"
for x := 0; x < l; x++ {
cells = addNoCells(cells)
width := 40 + (len(cells) >> 1)
fmt.Printf("%*s\n", width, cells)
cells = step(cells, rule)
}
}
func step(cells string, rule int) string {
newCells := new(strings.Builder)
for i := 0; i < len(cells)-2; i++ {
bin := 0
b := uint(2)
for n := i; n < i+3; n++ {
bin += btoi(cells[n] == 'O') << b
b >>= 1
}
a := '.'
if rule&(1<<uint(bin)) != 0 {
a = 'O'
}
newCells.WriteRune(a)
}
return newCells.String()
}
func addNoCells(cells string) string {
l, r := "O", "O"
if cells[0] == 'O' {
l = "."
}
if cells[len(cells)-1] == 'O' {
r = "."
}
cells = l + cells + r
cells = l + cells + r
return cells
}
func main() {
for _, r := range []int{90, 30} {
evolve(25, r)
fmt.Println()
}
} |
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).
| #Perl | Perl | use List::Util qw(none sum);
sub gcd { my ($u,$v) = @_; $v ? gcd($v, $u%$v) : abs($u) }
sub shares_divisors_with { gcd( $_[0], $_[1]) > 1 }
sub EKG {
my($n,$limit) = @_;
my @ekg = (1, $n);
while (@ekg < $limit) {
for my $i (2..1e18) {
next unless none { $_ == $i } @ekg and shares_divisors_with($ekg[-1], $i);
push(@ekg, $i) and last;
}
}
@ekg;
}
sub converge_at {
my($n1,$n2) = @_;
my $max = 100;
my @ekg1 = EKG($n1,$max);
my @ekg2 = EKG($n2,$max);
do { return $_+1 if $ekg1[$_] == $ekg2[$_] && sum(@ekg1[0..$_]) == sum(@ekg2[0..$_])} for 2..$max;
return "(no convergence in $max terms)";
}
print "EKG($_): " . join(' ', EKG($_,10)) . "\n" for 2, 5, 7, 9, 10;
print "EKGs of 5 & 7 converge at term " . converge_at(5, 7) . "\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
| #SNOBOL4 | SNOBOL4 | * ASSIGN THE NULL STRING TO X
X =
* CHECK THAT X IS INDEED NULL
EQ(X, NULL) :S(YES)
OUTPUT = 'NOT NULL' :(END)
YES OUTPUT = 'NULL'
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
| #Standard_ML | Standard ML | (* Assign empty string to a variable *)
val s = ""
(* Check that a string is empty*)
s = ""
(* Check that a string is nonempty *)
s <> "" |
http://rosettacode.org/wiki/Empty_program | Empty program | Task
Create the simplest possible program that is still considered "correct."
| #Programming_Language | Programming Language | |
http://rosettacode.org/wiki/Empty_program | Empty program | Task
Create the simplest possible program that is still considered "correct."
| #PSQL | PSQL | EXECUTE BLOCK
AS
BEGIN
END |
http://rosettacode.org/wiki/Empty_program | Empty program | Task
Create the simplest possible program that is still considered "correct."
| #PureBasic | PureBasic | |
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.
| #11l | 11l | T Node
Int length
Int suffix
[Char = Int] edges
F (length, suffix = 0)
.length = length
.suffix = suffix
-V oddRoot = 1
F eertree(s)
V tree = [Node(0, :oddRoot), Node(-1, :oddRoot)]
V suffix = :oddRoot
L(c) s
V i = L.index
V n = suffix
Int k
L
k = tree[n].length
V b = i - k - 1
I b >= 0 & s[b] == c
L.break
n = tree[n].suffix
V? edge = tree[n].edges.find(c)
I edge != N
suffix = edge
L.continue
suffix = tree.len
tree [+]= Node(k + 2)
tree[n].edges[c] = suffix
I tree[suffix].length == 1
tree[suffix].suffix = 0
L.continue
L
n = tree[n].suffix
V b = i - tree[n].length - 1
I b >= 0 & s[b] == c
L.break
tree[suffix].suffix = tree[n].edges[c]
R tree
F subPalindromes(tree)
[String] s
F children(Int n, String =p) -> N
L(c, n) @tree[n].edges
p = c‘’p‘’c
@s [+]= p
@children(n, p)
children(0, ‘’)
L(c, n) tree[1].edges
s [+]= c
children(n, c)
R s
V tree = eertree(‘eertree’)
print(subPalindromes(tree)) |
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
| #PicoLisp | PicoLisp | (de halve (N)
(/ N 2) )
(de double (N)
(* N 2) )
(de even? (N)
(not (bit? 1 N)) )
(de ethiopian (X Y)
(let R 0
(while (>= X 1)
(or (even? X) (inc 'R Y))
(setq
X (halve X)
Y (double Y) ) )
R ) ) |
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)
| #11l | 11l | V SIZE = 32
V LINES = SIZE I/ 2
V RULE = 90
F ruleTest(x)
R I :RULE [&] (1 << (7 [&] x)) != 0 {1} E 0
F bitVal(s, bit)
R I (s >> bit) [&] 1 != 0 {1} E 0
F evolve(&s)
V t = 0
t [|]= ruleTest((bitVal(s, 0) << 2) [|] (bitVal(s, :SIZE - 1) << 1) [|] bitVal(s, :SIZE - 2)) << (:SIZE - 1)
t [|]= ruleTest((bitVal(s, 1) << 2) [|] (bitVal(s, 0) << 1) [|] bitVal(s, :SIZE - 1))
L(i) 1 .< :SIZE - 1
t [|]= ruleTest((bitVal(s, i + 1) << 2) [|] (bitVal(s, i) << 1) [|] bitVal(s, i - 1)) << i
s = t
F show(state)
L(i) (:SIZE - 1 .. 0).step(-1)
print(‘ *’[bitVal(state, i)], end' ‘’)
print()
V state = 1 << LINES
print(‘Rule ’RULE)
L 1..LINES
show(state)
evolve(&state) |
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
| #SNOBOL4 | SNOBOL4 | define('rfact(n)') :(rfact_end)
rfact rfact = le(n,0) 1 :s(return)
rfact = n * rfact(n - 1) :(return)
rfact_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.
| #SETL | SETL | xs := {1..10};
evens := {x in xs | even( x )};
odds := {x in xs | odd( x )};
print( evens );
print( odds ); |
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.
| #Shen | Shen | (define even?
0 -> true
X -> (odd? (- X 1)))
(define odd?
0 -> false
X -> (even? (- X 1))) |
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.
| #C.23 | C# | using System.Net.Sockets;
using System.Threading;
namespace ConsoleApplication1
{
class Program
{
static TcpListener listen;
static Thread serverthread;
static void Main(string[] args)
{
listen = new TcpListener(System.Net.IPAddress.Parse("127.0.0.1"), 12321);
serverthread = new Thread(new ThreadStart(DoListen));
serverthread.Start();
}
private static void DoListen()
{
// Listen
listen.Start();
Console.WriteLine("Server: Started server");
while (true)
{
Console.WriteLine("Server: Waiting...");
TcpClient client = listen.AcceptTcpClient();
Console.WriteLine("Server: Waited");
// New thread with client
Thread clientThread = new Thread(new ParameterizedThreadStart(DoClient));
clientThread.Start(client);
}
}
private static void DoClient(object client)
{
// Read data
TcpClient tClient = (TcpClient)client;
Console.WriteLine("Client (Thread: {0}): Connected!", Thread.CurrentThread.ManagedThreadId);
do
{
if (!tClient.Connected)
{
tClient.Close();
Thread.CurrentThread.Abort(); // Kill thread.
}
if (tClient.Available > 0)
{
// Resend
byte pByte = (byte)tClient.GetStream().ReadByte();
Console.WriteLine("Client (Thread: {0}): Data {1}", Thread.CurrentThread.ManagedThreadId, pByte);
tClient.GetStream().WriteByte(pByte);
}
// Pause
Thread.Sleep(100);
} while (true);
}
}
} |
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.
| #Haskell | Haskell | {-# LANGUAGE DeriveFunctor #-}
import Control.Comonad
import Data.InfList (InfList (..), (+++))
import qualified Data.InfList as Inf
data Cells a = Cells (InfList a) a (InfList a) deriving Functor
view n (Cells l x r) = reverse (Inf.take n l) ++ [x] ++ (Inf.take n r)
fromList [] = fromList [0]
fromList (x:xs) = let zeros = Inf.repeat 0
in Cells zeros x (xs +++ zeros) |
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.
| #J | J | ext9=: (9#1-{.!.1),],9#1-{:!.1
trim=: |.@(}.~ ] i. 1-{.)^:2
next=: trim@(((8$2) #: [) {~ 2 #. 1 - [: |: |.~"1 0&_1 0 1@]) ext9 |
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.
| #jq | jq |
def lpad($len; $fill): tostring | ($len - length) as $l | ($fill * $l)[:$l] + .;
def lpad($len): lpad($len; " ");
# Like *ix `tr` but it is as though $to is padded with blanks
def tr($from;$to):
explode as $s
| ($from | explode) as $f
| ($to | explode) as $t
| reduce range(0;length) as $i ([];
($f | index($s[$i])) as $ix
| if $ix then . + [$t[$ix] // " "]
else . + [$s[$i]]
end )
| implode;
# Input: a non-negative integer
# Output: the corresponding stream of bits (0s and 1s),
# least significant digit first, with a final 0
def stream:
recurse(if . > 0 then ./2|floor else empty end) | . % 2 ;
# input: an array, e.g. as produced by [7|stream]
# output: the corresponding binary string
def to_b: reverse | map(tostring) | join("") | sub("^0";""); |
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).
| #Phix | Phix | with javascript_semantics
constant LIMIT = 100
constant starts = {2, 5, 7, 9, 10}
sequence ekg = {}
string fmt = "EKG(%2d): ["&join(repeat("%d",min(LIMIT,30))," ")&"]\n"
for s=1 to length(starts) do
ekg = append(ekg,{1,starts[s]}&repeat(0,LIMIT-2))
for n=3 to LIMIT do
-- a potential sequence member cannot already have been used
-- and must have a factor in common with previous member
integer i = 2
while find(i,ekg[s])
or gcd(ekg[s][n-1],i)<=1 do
i += 1
end while
ekg[s][n] = i
end for
printf(1,fmt,starts[s]&ekg[s][1..min(LIMIT,30)])
end for
-- now compare EKG5 and EKG7 for convergence
constant EKG5 = find(5,starts),
EKG7 = find(7,starts)
string msg = sprintf("do not converge within %d terms", LIMIT)
for i=3 to LIMIT do
if ekg[EKG5][i]=ekg[EKG7][i]
and sort(ekg[EKG5][1..i-1])=sort(ekg[EKG7][1..i-1]) then
msg = sprintf("converge at term %d", i)
exit
end if
end for
printf(1,"\nEKG5(5) and EKG(7) %s\n", msg)
|
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
| #Stata | Stata | scalar s=""
display s==""
* Alternatively, check the length
display length(s)==0 |
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
| #Swift | Swift | var s = ""
if s.isEmpty { // alternately, s == ""
println("s is empty")
} else {
println("s is not empty")
} |
http://rosettacode.org/wiki/Empty_program | Empty program | Task
Create the simplest possible program that is still considered "correct."
| #Python | Python | 1
QUIT |
http://rosettacode.org/wiki/Empty_program | Empty program | Task
Create the simplest possible program that is still considered "correct."
| #QUACKASM | QUACKASM | 1
QUIT |
http://rosettacode.org/wiki/Empty_program | Empty program | Task
Create the simplest possible program that is still considered "correct."
| #Quackery | Quackery | |
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.
| #C.23 | C# | using System;
using System.Collections.Generic;
namespace Eertree {
class Node {
public Node(int length) {
this.Length = length;
// empty or
this.Edges = new Dictionary<char, int>();
}
public Node(int length, Dictionary<char, int> edges, int suffix) {
this.Length = length;
this.Edges = edges;
this.Suffix = suffix;
}
public int Length { get; set; }
public Dictionary<char, int> Edges { get; set; }
public int Suffix { get; set; }
}
class Program {
const int EVEN_ROOT = 0;
const int ODD_ROOT = 1;
static List<Node> Eertree(string s) {
List<Node> tree = new List<Node> {
//new Node(0, null, ODD_ROOT), or
new Node(0, new Dictionary<char, int>(), ODD_ROOT),
//new Node(-1, null, ODD_ROOT) or
new Node(-1, new Dictionary<char, int>(), ODD_ROOT)
};
int suffix = ODD_ROOT;
int n, k;
for (int i = 0; i < s.Length; i++) {
char c = s[i];
for (n = suffix; ; n = tree[n].Suffix) {
k = tree[n].Length;
int b = i - k - 1;
if (b >= 0 && s[b] == c) {
break;
}
}
if (tree[n].Edges.ContainsKey(c)) {
suffix = tree[n].Edges[c];
continue;
}
suffix = tree.Count;
tree.Add(new Node(k + 2));
tree[n].Edges[c] = suffix;
if (tree[suffix].Length == 1) {
tree[suffix].Suffix = 0;
continue;
}
while (true) {
n = tree[n].Suffix;
int b = i - tree[n].Length - 1;
if (b >= 0 && s[b] == c) {
break;
}
}
tree[suffix].Suffix = tree[n].Edges[c];
}
return tree;
}
static List<string> SubPalindromes(List<Node> tree) {
List<string> s = new List<string>();
SubPalindromes_children(0, "", tree, s);
foreach (var c in tree[1].Edges.Keys) {
int m = tree[1].Edges[c];
string ct = c.ToString();
s.Add(ct);
SubPalindromes_children(m, ct, tree, s);
}
return s;
}
static void SubPalindromes_children(int n, string p, List<Node> tree, List<string> s) {
foreach (var c in tree[n].Edges.Keys) {
int m = tree[n].Edges[c];
string p1 = c + p + c;
s.Add(p1);
SubPalindromes_children(m, p1, tree, s);
}
}
static void Main(string[] args) {
List<Node> tree = Eertree("eertree");
List<string> result = SubPalindromes(tree);
string listStr = string.Join(", ", result);
Console.WriteLine("[{0}]", listStr);
}
}
} |
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
| #Pike | Pike | int ethopian_multiply(int l, int r)
{
int halve(int n) { return n/2; };
int double(int n) { return n*2; };
int(0..1) evenp(int n) { return !(n%2); };
int product = 0;
do
{
write("%5d %5d\n", l, r);
if (!evenp(l))
product += r;
l = halve(l);
r = double(r);
}
while(l);
return 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)
| #Action.21 | Action! | DEFINE ROW_LEN="320"
DEFINE MAX_COL="319"
DEFINE MAX_ROW="191"
PROC GenerateMask(BYTE rule BYTE ARRAY mask)
BYTE i
FOR i=0 TO 7
DO
mask(i)=rule&1
rule==RSH 1
OD
RETURN
PROC InitRow(BYTE ARRAY row)
INT c
FOR c=0 TO MAX_COL
DO
row(c)=0
OD
row(ROW_LEN RSH 1)=1
RETURN
PROC DrawRow(BYTE ARRAY row BYTE y)
INT c
FOR c=0 TO MAX_COL
DO
Color=row(c)
Plot(c,y)
OD
RETURN
PROC CalcNextRow(BYTE ARRAY currRow,nextRow,mask)
INT c
BYTE v
v=currRow(MAX_COL) LSH 2
v==%currRow(0) LSH 1
v==%currRow(1)
nextRow(0)=mask(v)
FOR c=1 TO MAX_COL-1
DO
v==&3
v==LSH 1
v==%currRow(c+1)
nextRow(c)=mask(v)
OD
v==&3
v==LSH 1
v==%currRow(0)
nextRow(MAX_COL)=mask(v)
RETURN
PROC DrawRule(BYTE rule)
BYTE ARRAY row1(ROW_LEN),row2(ROW_LEN),mask(8)
BYTE ARRAY currRow,nextRow,tmp
BYTE y
GenerateMask(rule,mask)
currRow=row1
nextRow=row2
InitRow(currRow)
y=0
WHILE y<=MAX_ROW
DO
DrawRow(currRow,y)
CalcNextRow(currRow,nextRow,mask)
tmp=currRow currRow=nextRow nextRow=tmp
y==+1
OD
RETURN
PROC Main()
BYTE CH=$02FC,COLOR1=$02C5,COLOR2=$02C6
Graphics(8+16)
Color=1
COLOR1=$0C
COLOR2=$02
DrawRule(30)
DO UNTIL CH#$FF OD
CH=$FF
RETURN |
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)
| #Ada | Ada | with Ada.Text_IO;
procedure Elementary_Cellular_Automaton is
type t_Rule is new Integer range 0..2**8-1;
type t_State is array (Integer range <>) of Boolean;
Cell_Image : constant array (Boolean) of Character := ('.', '#');
function Image (State : in t_State) return String is
(Cell_Image(State(State'First)) &
(if State'Length <= 1 then ""
else Image(State(State'First+1..State'Last))));
-- More convenient representation of the rule
type t_RuleA is array (Boolean, Boolean, Boolean) of Boolean;
function Translate (Rule : in t_Rule) return t_RuleA is
-- Better not use Pack attribute and Unchecked_Conversion
-- because it would not be endianness independent...
Remain : t_Rule := Rule;
begin
return Answer : t_RuleA do
for K in Boolean loop
for J in Boolean loop
for I in Boolean loop
Answer(I,J,K) := (Remain mod 2 = 1);
Remain := Remain / 2;
end loop;
end loop;
end loop;
end return;
end Translate;
procedure Show_Automaton (Rule : in t_Rule;
Initial : in t_State;
Generations : in Positive) is
RuleA : constant t_RuleA := Translate(Rule);
Width : constant Positive := Initial'Length;
-- More convenient indices for neighbor wraparound with "mod"
subtype t_State0 is t_State (0..Width-1);
State : t_State0 := Initial;
New_State : t_State0;
begin
Ada.Text_IO.Put_Line ("Rule" & t_Rule'Image(Rule) & " :");
for Generation in 1..Generations loop
Ada.Text_IO.Put_Line (Image(State));
for Cell in State'Range loop
New_State(Cell) := RuleA(State((Cell-1) mod Width),
State(Cell),
State((Cell+1) mod Width));
end loop;
State := New_State;
end loop;
end Show_Automaton;
begin
Show_Automaton (Rule => 90,
Initial => (-10..-1 => False, 0 => True, 1..10 => False),
Generations => 15);
Show_Automaton (Rule => 30,
Initial => (-15..-1 => False, 0 => True, 1..15 => False),
Generations => 20);
Show_Automaton (Rule => 122,
Initial => (-12..-1 => False, 0 => True, 1..12 => False),
Generations => 25);
end Elementary_Cellular_Automaton;
|
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
| #Spin | Spin | con
_clkmode = xtal1 + pll16x
_clkfreq = 80_000_000
obj
ser : "FullDuplexSerial.spin"
pub main | i
ser.start(31, 30, 0, 115200)
repeat i from 0 to 10
ser.dec(fac(i))
ser.tx(32)
waitcnt(_clkfreq + cnt)
ser.stop
cogstop(0)
pub fac(n) : f
f := 1
repeat while n > 0
f *= n
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.
| #Sidef | Sidef | var n = 42;
say n.is_odd; # false
say n.is_even; # true |
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.
| #Smalltalk | Smalltalk | 5 even
5 odd |
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.
| #Clojure | Clojure | (use '[clojure.contrib.server-socket :only (create-server)])
(use '[clojure.contrib.duck-streams :only (read-lines write-lines)])
(defn echo [input output]
(write-lines (java.io.PrintWriter. output true) (read-lines input)))
(create-server 12321 echo) |
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.
| #Julia | Julia | function ecainfinite(cells, rule, n)
notcell(cell) = (cell == '1') ? '0' : '1'
rulebits = reverse(string(rule, base = 2, pad = 8))
neighbors2next = Dict(string(n - 1, base=2, pad=3) => rulebits[n] for n in 1:8)
ret = String[]
for i in 1:n
push!(ret, cells)
cells = notcell(cells[1])^2 * cells * notcell(cells[end])^2 # Extend/pad ends
cells = join([neighbors2next[cells[i:i+2]] for i in 1:length(cells)-2], "")
end
ret
end
function testinfcells(lines::Integer)
for rule in [90, 30]
println("\nRule: $rule ($(string(rule, base = 2, pad = 8)))")
s = ecainfinite("1", rule, lines)
for i in 1:lines
println("$i: ", " "^(lines - i), replace(replace(s[i], "0" => "."), "1" => "#"))
end
end
end
testinfcells(25)
|
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.
| #Kotlin | Kotlin | // version 1.1.51
fun evolve(l: Int, rule: Int) {
println(" Rule #$rule:")
var cells = StringBuilder("*")
for (x in 0 until l) {
addNoCells(cells)
val width = 40 + (cells.length shr 1)
println(cells.padStart(width))
cells = step(cells, rule)
}
}
fun step(cells: StringBuilder, rule: Int): StringBuilder {
val newCells = StringBuilder()
for (i in 0 until cells.length - 2) {
var bin = 0
var b = 2
for (n in i until i + 3) {
bin += (if (cells[n] == '*') 1 else 0) shl b
b = b shr 1
}
val a = if ((rule and (1 shl bin)) != 0) '*' else '.'
newCells.append(a)
}
return newCells
}
fun addNoCells(s: StringBuilder) {
val l = if (s[0] == '*') '.' else '*'
val r = if (s[s.length - 1] == '*') '.' else '*'
repeat(2) {
s.insert(0, l)
s.append(r)
}
}
fun main(args: Array<String>) {
evolve(35, 90)
println()
} |
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).
| #Python | Python | from itertools import count, islice, takewhile
from math import gcd
def EKG_gen(start=2):
"""\
Generate the next term of the EKG together with the minimum cache of
numbers left in its production; (the "state" of the generator).
Using math.gcd
"""
c = count(start + 1)
last, so_far = start, list(range(2, start))
yield 1, []
yield last, []
while True:
for index, sf in enumerate(so_far):
if gcd(last, sf) > 1:
last = so_far.pop(index)
yield last, so_far[::]
break
else:
so_far.append(next(c))
def find_convergence(ekgs=(5,7)):
"Returns the convergence point or zero if not found within the limit"
ekg = [EKG_gen(n) for n in ekgs]
for e in ekg:
next(e) # skip initial 1 in each sequence
return 2 + len(list(takewhile(lambda state: not all(state[0] == s for s in state[1:]),
zip(*ekg))))
if __name__ == '__main__':
for start in 2, 5, 7, 9, 10:
print(f"EKG({start}):", str([n[0] for n in islice(EKG_gen(start), 10)])[1: -1])
print(f"\nEKG(5) and EKG(7) converge at term {find_convergence(ekgs=(5,7))}!") |
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
| #Tcl | Tcl | set s ""
if {$s eq ""} {puts "s contains an empty string"}
if {$s ne ""} {puts "s contains a non-empty string"} |
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
| #TorqueScript | TorqueScript | $empty = "";
|
http://rosettacode.org/wiki/Empty_program | Empty program | Task
Create the simplest possible program that is still considered "correct."
| #Quite_BASIC | Quite BASIC | |
http://rosettacode.org/wiki/Empty_program | Empty program | Task
Create the simplest possible program that is still considered "correct."
| #R | R |
#lang racket
|
http://rosettacode.org/wiki/Empty_program | Empty program | Task
Create the simplest possible program that is still considered "correct."
| #Racket | Racket |
#lang racket
|
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.
| #C.2B.2B | C++ | #include <iostream>
#include <functional>
#include <map>
#include <vector>
struct Node {
int length;
std::map<char, int> edges;
int suffix;
Node(int l) : length(l), suffix(0) {
/* empty */
}
Node(int l, const std::map<char, int>& m, int s) : length(l), edges(m), suffix(s) {
/* empty */
}
};
constexpr int evenRoot = 0;
constexpr int oddRoot = 1;
std::vector<Node> eertree(const std::string& s) {
std::vector<Node> tree = {
Node(0, {}, oddRoot),
Node(-1, {}, oddRoot)
};
int suffix = oddRoot;
int n, k;
for (size_t i = 0; i < s.length(); ++i) {
char c = s[i];
for (n = suffix; ; n = tree[n].suffix) {
k = tree[n].length;
int b = i - k - 1;
if (b >= 0 && s[b] == c) {
break;
}
}
auto it = tree[n].edges.find(c);
auto end = tree[n].edges.end();
if (it != end) {
suffix = it->second;
continue;
}
suffix = tree.size();
tree.push_back(Node(k + 2));
tree[n].edges[c] = suffix;
if (tree[suffix].length == 1) {
tree[suffix].suffix = 0;
continue;
}
while (true) {
n = tree[n].suffix;
int b = i - tree[n].length - 1;
if (b >= 0 && s[b] == c) {
break;
}
}
tree[suffix].suffix = tree[n].edges[c];
}
return tree;
}
std::vector<std::string> subPalindromes(const std::vector<Node>& tree) {
std::vector<std::string> s;
std::function<void(int, std::string)> children;
children = [&children, &tree, &s](int n, std::string p) {
auto it = tree[n].edges.cbegin();
auto end = tree[n].edges.cend();
for (; it != end; it = std::next(it)) {
auto c = it->first;
auto m = it->second;
std::string pl = c + p + c;
s.push_back(pl);
children(m, pl);
}
};
children(0, "");
auto it = tree[1].edges.cbegin();
auto end = tree[1].edges.cend();
for (; it != end; it = std::next(it)) {
auto c = it->first;
auto n = it->second;
std::string ct(1, c);
s.push_back(ct);
children(n, ct);
}
return s;
}
int main() {
using namespace std;
auto tree = eertree("eertree");
auto pal = subPalindromes(tree);
auto it = pal.cbegin();
auto end = pal.cend();
cout << "[";
if (it != end) {
cout << it->c_str();
it++;
}
while (it != end) {
cout << ", " << it->c_str();
it++;
}
cout << "]" << endl;
return 0;
} |
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
| #PL.2FI | PL/I |
declare (L(30), R(30)) fixed binary;
declare (i, s) fixed binary;
L, R = 0;
put skip list
('Hello, please type two values and I will print their product:');
get list (L(1), R(1));
put edit ('The product of ', trim(L(1)), ' and ', trim(R(1)), ' is ') (a);
do i = 1 by 1 while (L(i) ^= 0);
L(i+1) = halve(L(i));
R(i+1) = double(R(i));
end;
s = 0;
do i = 1 by 1 while (L(i) > 0);
if odd(L(i)) then s = s + R(i);
end;
put edit (trim(s)) (a);
halve: procedure (k) returns (fixed binary);
declare k fixed binary;
return (k/2);
end halve;
double: procedure (k) returns (fixed binary);
declare k fixed binary;
return (2*k);
end;
odd: procedure (k) returns (bit (1));
return (iand(k, 1) ^= 0);
end odd; |
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)
| #ALGOL_68 | ALGOL 68 | BEGIN # elementary cellular automaton #
COMMENT returns the next state from state using rule; s must be at least 2 characters long and consist of # and - only COMMENT
PROC next state = ( STRING state, INT rule )STRING:
BEGIN
COMMENT returns 1 or 0 depending on whether c = # or not COMMENT
OP TOINT = ( CHAR c )INT: IF c = "#" THEN 1 ELSE 0 FI;
# construct the state with additional extra elements to allow wrap-around #
STRING s = state[ UPB state ] + state + state[ LWB state : LWB state + 1 ];
COMMENT convert rule to a string of # or - depending on whether the bits of r are on or off COMMENT
STRING r := "";
INT v := rule;
FOR i TO 8 DO
r +:= IF ODD v THEN "#" ELSE "-" FI;
v OVERAB 2
OD;
STRING new state := "";
FOR i FROM LWB s TO UPB s - 3 DO
CHAR c1 = s[ i ];
CHAR c2 = s[ i + 1 ];
CHAR c3 = s[ i + 2 ];
INT pos := ( ( ( TOINT c1 * 2 ) + TOINT c2 ) * 2 ) + TOINT c3;
new state +:= r[ pos + 1 ]
OD;
new state
END # next state # ;
# evolve state until the next state = the current state or 10 iterations have occured #
PROC test = ( STRING state, INT rule )VOID:
BEGIN
print( ( "Rule ", whole( rule, 0 ), newline ) );
STRING curr := state;
print( ( " 0: ", curr, newline ) );
FOR i TO 10 WHILE STRING next = next state( curr, rule );
next /= curr
DO
print( ( whole( i, -2 ), ": ", next, newline ) );
curr := next
OD
END # test # ;
# tests #
test( "---------#---------", 30 );
test( "---------#---------", 60 );
test( "---------#---------", 90 )
END |
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
| #SPL | SPL | fact(n)=
? n!>1, <=1
<= n*fact(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.
| #SNOBOL4 | SNOBOL4 | DEFINE('even(n)') :(even_end)
even even = (EQ(REMDR(n, 2), 0) 'even', 'odd') :(RETURN)
even_end
OUTPUT = "-2 is " even(-2)
OUTPUT = "-1 is " even(-1)
OUTPUT = "0 is " even(0)
OUTPUT = "1 is " even(1)
OUTPUT = "2 is " even(2)
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.
| #SNUSP | SNUSP |
$====!/?\==even#
- -
#odd==\?/
|
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.
| #CoffeeScript | CoffeeScript |
net = require("net")
server = net.createServer (conn) ->
console.log "Connection from #{conn.remoteAddress} on port #{conn.remotePort}"
conn.setEncoding "utf8"
buffer = ""
conn.on "data", (data) ->
i = 0
while i <= data.length
char = data.charAt(i)
buffer += char
if char is "\n"
conn.write buffer
buffer = ""
i++
server.listen 12321, "localhost"
|
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.
| #Mathematica_.2F_Wolfram_Language | Mathematica / Wolfram Language | CellularAutomaton[18, {{1}, 0}, 15] // ArrayPlot
CellularAutomaton[30, {{1}, 0}, 15] // ArrayPlot |
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.
| #Nim | Nim | import strutils
func step(cells: string; rule: int): string =
for i in 0..(cells.len - 3):
var bin = 0
var b = 2
for n in i..(i + 2):
inc bin, ord(cells[n] == '*') shl b
b = b shr 1
let a = if (rule and 1 shl bin) != 0: '*' else: '.'
result.add(a)
func addNoCells(cells: var string) =
let left = if cells[0] == '*': "." else: "*"
let right = if cells[^1] == '*': "." else: "*"
cells.insert(left)
cells.add(right)
cells.insert(left)
cells.add(right)
proc evolve(limit, rule: int) =
echo "Rule #", rule
var cells = "*"
for _ in 0..<limit:
cells.addNoCells()
let width = 40 + cells.len shr 1
echo cells.align(width)
cells = cells.step(rule)
evolve(35, 90) |
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.
| #Perl | Perl | sub evolve {
my ($rule, $pattern) = @_;
my $offset = 0;
while (1) {
my ($l, $r, $st);
$pattern =~ s/^((.)\g2*)/$2$2/ and $l = $2, $offset -= length($2);
$pattern =~ s/(.)\g1*$/$1$1/ and $r = $1;
$st = $pattern;
$pattern =~ tr/01/.#/;
printf "%5d| %s%s\n", $offset, ' ' x (40 + $offset), $pattern;
$pattern = join '', map(1 & ($rule>>oct "0b$_"),
$l x 3,
map(substr($st, $_, 3), 0 .. length($st)-3),
$r x 3);
}
}
evolve(90, "010"); |
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).
| #Raku | Raku | sub infix:<shares-divisors-with> { ($^a gcd $^b) > 1 }
sub next-EKG ( *@s ) {
return first {
@s ∌ $_ and @s.tail shares-divisors-with $_
}, 2..*;
}
sub EKG ( Int $start ) { 1, $start, &next-EKG … * }
sub converge-at ( @ints ) {
my @ekgs = @ints.map: &EKG;
return (2 .. *).first: -> $i {
[==] @ekgs.map( *.[$i] ) and
[===] @ekgs.map( *.head($i).Set )
}
}
say "EKG($_): ", .&EKG.head(10) for 2, 5, 7, 9, 10;
for [5, 7], [2, 5, 7, 9, 10] -> @ints {
say "EKGs of (@ints[]) converge at term {$_+1}" with converge-at(@ints);
} |
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
| #TUSCRIPT | TUSCRIPT |
$$ MODE TUSCRIPT
s=""
IF (s=="") PRINT "s is an empty string"
IF (s!="") PRINT "s is a non-empty string"
|
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
| #TXR | TXR | @(bind a "") |
http://rosettacode.org/wiki/Empty_program | Empty program | Task
Create the simplest possible program that is still considered "correct."
| #Raku | Raku | |
http://rosettacode.org/wiki/Empty_program | Empty program | Task
Create the simplest possible program that is still considered "correct."
| #Raven | Raven | rebol [] |
http://rosettacode.org/wiki/Empty_program | Empty program | Task
Create the simplest possible program that is still considered "correct."
| #REBOL | REBOL | rebol [] |
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.
| #Ada | Ada | with Ada.Text_IO, Matrix_Scalar;
procedure Scalar_Ops is
subtype T is Integer range 1 .. 3;
package M is new Matrix_Scalar(T, T, Integer);
-- the functions to solve the task
function "+" is new M.Func("+");
function "-" is new M.Func("-");
function "*" is new M.Func("*");
function "/" is new M.Func("/");
function "**" is new M.Func("**");
function "mod" is new M.Func("mod");
-- for output purposes, we need a Matrix->String conversion
function Image is new M.Image(Integer'Image);
A: M.Matrix := ((1,2,3),(4,5,6),(7,8,9)); -- something to begin with
begin
Ada.Text_IO.Put_Line(" Initial M=" & Image(A));
Ada.Text_IO.Put_Line(" M+2=" & Image(A+2));
Ada.Text_IO.Put_Line(" M-2=" & Image(A-2));
Ada.Text_IO.Put_Line(" M*2=" & Image(A*2));
Ada.Text_IO.Put_Line(" M/2=" & Image(A/2));
Ada.Text_IO.Put_Line(" square(M)=" & Image(A ** 2));
Ada.Text_IO.Put_Line(" M mod 2=" & Image(A mod 2));
Ada.Text_IO.Put_Line("(M*2) mod 3=" & Image((A*2) mod 3));
end Scalar_Ops; |
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.
| #D | D | import std.array;
import std.stdio;
void main() {
auto tree = eertree("eertree");
writeln(subPalindromes(tree));
}
struct Node {
int length;
int[char] edges;
int suffix;
}
const evenRoot = 0;
const oddRoot = 1;
Node[] eertree(string s) {
Node[] tree = [
Node(0, null, oddRoot),
Node(-1, null, oddRoot),
];
int suffix = oddRoot;
int n, k;
foreach (i, c; s) {
for (n=suffix; ; n=tree[n].suffix) {
k = tree[n].length;
int b = i-k-1;
if (b>=0 && s[b]==c) {
break;
}
}
if (c in tree[n].edges) {
suffix = tree[n].edges[c];
continue;
}
suffix = tree.length;
tree ~= Node(k+2);
tree[n].edges[c] = suffix;
if (tree[suffix].length == 1) {
tree[suffix].suffix = 0;
continue;
}
while (true) {
n = tree[n].suffix;
int b = i-tree[n].length-1;
if (b>=0 && s[b]==c) {
break;
}
}
tree[suffix].suffix = tree[n].edges[c];
}
return tree;
}
auto subPalindromes(Node[] tree) {
auto s = appender!(string[]);
void children(int n, string p) {
foreach (c, n; tree[n].edges) {
p = c ~ p ~ c;
s ~= p;
children(n, p);
}
}
children(0, "");
foreach (c, n; tree[1].edges) {
string ct = [c].idup;
s ~= ct;
children(n, ct);
}
return s.data;
} |
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
| #PL.2FSQL | PL/SQL | CREATE OR REPLACE PACKAGE ethiopian IS
FUNCTION multiply
( left IN INTEGER,
right IN INTEGER)
RETURN INTEGER;
END ethiopian;
/
CREATE OR REPLACE PACKAGE BODY ethiopian IS
FUNCTION is_even(item IN INTEGER) RETURN BOOLEAN IS
BEGIN
RETURN item MOD 2 = 0;
END is_even;
FUNCTION double(item IN INTEGER) RETURN INTEGER IS
BEGIN
RETURN item * 2;
END double;
FUNCTION half(item IN INTEGER) RETURN INTEGER IS
BEGIN
RETURN TRUNC(item / 2);
END half;
FUNCTION multiply
( left IN INTEGER,
right IN INTEGER)
RETURN INTEGER
IS
temp INTEGER := 0;
plier INTEGER := left;
plicand INTEGER := right;
BEGIN
LOOP
IF NOT is_even(plier) THEN
temp := temp + plicand;
END IF;
EXIT WHEN plier <= 1;
plier := half(plier);
plicand := double(plicand);
END LOOP;
RETURN temp;
END multiply;
END ethiopian;
/
/* example call */
BEGIN
DBMS_OUTPUT.put_line(ethiopian.multiply(17, 34));
END;
/ |
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)
| #AutoHotkey | AutoHotkey | state := StrSplit("0000000001000000000")
rule := 90
output := "Rule: " rule
Loop, 10 {
output .= "`n" A_Index "`t" PrintState(state)
state := NextState(state, rule)
}
Gui, Font,, Courier New
Gui, Add, Text,, % output
Gui, Show
return
GuiClose:
ExitApp
; Returns the next state based on the current state and rule.
NextState(state, rule) {
r := ByteDigits(rule)
result := {}
for i, val in state {
if (i = 1) ; The leftmost cell
result.Insert(r[state[state.MaxIndex()] state.1 state.2])
else if (i = state.MaxIndex()) ; The rightmost cell
result.Insert(r[state[i-1] val state.1])
else ; All cells between leftmost and rightmost
result.Insert(r[state[i - 1] val state[i + 1]])
}
return result
}
; Returns an array with each three digit sequence as a key corresponding to a value
; of true or false depending on the rule.
ByteDigits(rule) {
res := {}
for i, val in ["000", "001", "010", "011", "100", "101", "110", "111"] {
res[val] := Mod(rule, 2)
rule >>= 1
}
return res
}
; Converts 0 and 1 to . and # respectively and returns a string representing the state
PrintState(state) {
for i, val in state
result .= val = 1 ? "#" : "."
return result
} |
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
| #SSEM | SSEM | 11100000000000100000000000000000 0. -7 to c
10101000000000010000000000000000 1. Sub. 21
10100000000001100000000000000000 2. c to 5
10100000000000100000000000000000 3. -5 to c
10100000000001100000000000000000 4. c to 5
00000000000000000000000000000000 5. generated at run time
00000000000001110000000000000000 6. Stop
00010000000000100000000000000000 7. -8 to c
11111111111111111111111111111111 8. -1
11111111111111111111111111111111 9. -1
01111111111111111111111111111111 10. -2
01011111111111111111111111111111 11. -6
00010111111111111111111111111111 12. -24
00010001111111111111111111111111 13. -120
00001100101111111111111111111111 14. -720
00001010001101111111111111111111 15. -5040
00000001010001101111111111111111 16. -40320
00000001011011100101111111111111 17. -362880
00000000100001010001001111111111 18. -3628800
00000000110101110111100110111111 19. -39916800
00000000001000001100111011000111 20. -479001600
01010000000000000000000000000000 21. 10 |
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.
| #SPL | SPL | > n, 0..9
? #.even(n), #.output(n," even")
? #.odd(n), #.output(n," odd")
< |
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.
| #SQL | SQL | -- Setup a table with some integers
CREATE TABLE ints(INT INTEGER);
INSERT INTO ints VALUES (-1);
INSERT INTO ints VALUES (0);
INSERT INTO ints VALUES (1);
INSERT INTO ints VALUES (2);
-- Are they even or odd?
SELECT
INT,
CASE MOD(INT, 2) WHEN 0 THEN 'Even' ELSE 'Odd' END
FROM
ints; |
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