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http://rosettacode.org/wiki/Vector_products | Vector products | A vector is defined as having three dimensions as being represented by an ordered collection of three numbers: (X, Y, Z).
If you imagine a graph with the x and y axis being at right angles to each other and having a third, z axis coming out of the page, then a triplet of numbers, (X, Y, Z) would represent a point in the region, and a vector from the origin to the point.
Given the vectors:
A = (a1, a2, a3)
B = (b1, b2, b3)
C = (c1, c2, c3)
then the following common vector products are defined:
The dot product (a scalar quantity)
A • B = a1b1 + a2b2 + a3b3
The cross product (a vector quantity)
A x B = (a2b3 - a3b2, a3b1 - a1b3, a1b2 - a2b1)
The scalar triple product (a scalar quantity)
A • (B x C)
The vector triple product (a vector quantity)
A x (B x C)
Task
Given the three vectors:
a = ( 3, 4, 5)
b = ( 4, 3, 5)
c = (-5, -12, -13)
Create a named function/subroutine/method to compute the dot product of two vectors.
Create a function to compute the cross product of two vectors.
Optionally create a function to compute the scalar triple product of three vectors.
Optionally create a function to compute the vector triple product of three vectors.
Compute and display: a • b
Compute and display: a x b
Compute and display: a • (b x c), the scalar triple product.
Compute and display: a x (b x c), the vector triple product.
References
A starting page on Wolfram MathWorld is Vector Multiplication .
Wikipedia dot product.
Wikipedia cross product.
Wikipedia triple product.
Related tasks
Dot product
Quaternion type
| #Rust | Rust | #[derive(Debug)]
struct Vector {
x: f64,
y: f64,
z: f64,
}
impl Vector {
fn new(x: f64, y: f64, z: f64) -> Self {
Vector {
x: x,
y: y,
z: z,
}
}
fn dot_product(&self, other: &Vector) -> f64 {
(self.x * other.x) + (self.y * other.y) + (self.z * other.z)
}
fn cross_product(&self, other: &Vector) -> Vector {
Vector::new(self.y * other.z - self.z * other.y,
self.z * other.x - self.x * other.z,
self.x * other.y - self.y * other.x)
}
fn scalar_triple_product(&self, b: &Vector, c: &Vector) -> f64 {
self.dot_product(&b.cross_product(&c))
}
fn vector_triple_product(&self, b: &Vector, c: &Vector) -> Vector {
self.cross_product(&b.cross_product(&c))
}
}
fn main(){
let a = Vector::new(3.0, 4.0, 5.0);
let b = Vector::new(4.0, 3.0, 5.0);
let c = Vector::new(-5.0, -12.0, -13.0);
println!("a . b = {}", a.dot_product(&b));
println!("a x b = {:?}", a.cross_product(&b));
println!("a . (b x c) = {}", a.scalar_triple_product(&b, &c));
println!("a x (b x c) = {:?}", a.vector_triple_product(&b, &c));
} |
http://rosettacode.org/wiki/User_input/Text | User input/Text | User input/Text is part of Short Circuit's Console Program Basics selection.
Task
Input a string and the integer 75000 from the text console.
See also: User input/Graphical
| #Wee_Basic | Wee Basic | print 1 "Enter a string."
input string$
print 1 "Enter an integer."
input integer |
http://rosettacode.org/wiki/User_input/Text | User input/Text | User input/Text is part of Short Circuit's Console Program Basics selection.
Task
Input a string and the integer 75000 from the text console.
See also: User input/Graphical
| #Wren | Wren | import "io" for Stdin, Stdout
var string
while (true) {
System.write("Enter a string : ")
Stdout.flush()
string = Stdin.readLine()
if (string.count == 0) {
System.print("String cannot be empty, try again.")
} else {
break
}
}
var number
while (true) {
System.write("Enter a number : ")
Stdout.flush()
number = Num.fromString(Stdin.readLine())
if (!number || !number.isInteger) {
System.print("Please enter a vaid integer, try again.")
} else {
break
}
}
System.print("\nYou entered:")
System.print(" string: %(string)")
System.print(" number: %(number)") |
http://rosettacode.org/wiki/Undefined_values | Undefined values | #Pascal | Pascal | #!/usr/bin/perl -w
use strict;
# Declare the variable. It is initialized to the value "undef"
our $var;
# Check to see whether it is defined
print "var contains an undefined value at first check\n" unless defined $var;
# Give it a value
$var = "Chocolate";
# Check to see whether it is defined after we gave it the
# value "Chocolate"
print "var contains an undefined value at second check\n" unless defined $var;
# Give the variable the value "undef".
$var = undef;
# or, equivalently:
undef($var);
# Check to see whether it is defined after we've explicitly
# given it an undefined value.
print "var contains an undefined value at third check\n" unless defined $var;
# Give the variable a value of 42
$var = 42;
# Check to see whether the it is defined after we've given it
# the value 42.
print "var contains an undefined value at fourth check\n" unless defined $var;
# Because most of the output is conditional, this serves as
# a clear indicator that the program has run to completion.
print "Done\n"; |
|
http://rosettacode.org/wiki/Undefined_values | Undefined values | #Perl | Perl | #!/usr/bin/perl -w
use strict;
# Declare the variable. It is initialized to the value "undef"
our $var;
# Check to see whether it is defined
print "var contains an undefined value at first check\n" unless defined $var;
# Give it a value
$var = "Chocolate";
# Check to see whether it is defined after we gave it the
# value "Chocolate"
print "var contains an undefined value at second check\n" unless defined $var;
# Give the variable the value "undef".
$var = undef;
# or, equivalently:
undef($var);
# Check to see whether it is defined after we've explicitly
# given it an undefined value.
print "var contains an undefined value at third check\n" unless defined $var;
# Give the variable a value of 42
$var = 42;
# Check to see whether the it is defined after we've given it
# the value 42.
print "var contains an undefined value at fourth check\n" unless defined $var;
# Because most of the output is conditional, this serves as
# a clear indicator that the program has run to completion.
print "Done\n"; |
|
http://rosettacode.org/wiki/Unicode_strings | Unicode strings | As the world gets smaller each day, internationalization becomes more and more important. For handling multiple languages, Unicode is your best friend.
It is a very capable tool, but also quite complex compared to older single- and double-byte character encodings.
How well prepared is your programming language for Unicode?
Task
Discuss and demonstrate its unicode awareness and capabilities.
Some suggested topics:
How easy is it to present Unicode strings in source code?
Can Unicode literals be written directly, or be part of identifiers/keywords/etc?
How well can the language communicate with the rest of the world?
Is it good at input/output with Unicode?
Is it convenient to manipulate Unicode strings in the language?
How broad/deep does the language support Unicode?
What encodings (e.g. UTF-8, UTF-16, etc) can be used?
Does it support normalization?
Note
This task is a bit unusual in that it encourages general discussion rather than clever coding.
See also
Unicode variable names
Terminal control/Display an extended character
| #jq | jq | --raw-input | -R :: each line of input is converted to a JSON string;
--ascii-output | -a :: every non-ASCII character that would otherwise
be sent to output is translated to an equivalent
ASCII escape sequence;
--raw-output | -r :: output strings as raw strings, e.g. "a\nb" is
output as:
|
http://rosettacode.org/wiki/Unicode_strings | Unicode strings | As the world gets smaller each day, internationalization becomes more and more important. For handling multiple languages, Unicode is your best friend.
It is a very capable tool, but also quite complex compared to older single- and double-byte character encodings.
How well prepared is your programming language for Unicode?
Task
Discuss and demonstrate its unicode awareness and capabilities.
Some suggested topics:
How easy is it to present Unicode strings in source code?
Can Unicode literals be written directly, or be part of identifiers/keywords/etc?
How well can the language communicate with the rest of the world?
Is it good at input/output with Unicode?
Is it convenient to manipulate Unicode strings in the language?
How broad/deep does the language support Unicode?
What encodings (e.g. UTF-8, UTF-16, etc) can be used?
Does it support normalization?
Note
This task is a bit unusual in that it encourages general discussion rather than clever coding.
See also
Unicode variable names
Terminal control/Display an extended character
| #Julia | Julia | julia> 四十二 = "voilà";
julia> println(四十二)
voilà |
http://rosettacode.org/wiki/Unicode_strings | Unicode strings | As the world gets smaller each day, internationalization becomes more and more important. For handling multiple languages, Unicode is your best friend.
It is a very capable tool, but also quite complex compared to older single- and double-byte character encodings.
How well prepared is your programming language for Unicode?
Task
Discuss and demonstrate its unicode awareness and capabilities.
Some suggested topics:
How easy is it to present Unicode strings in source code?
Can Unicode literals be written directly, or be part of identifiers/keywords/etc?
How well can the language communicate with the rest of the world?
Is it good at input/output with Unicode?
Is it convenient to manipulate Unicode strings in the language?
How broad/deep does the language support Unicode?
What encodings (e.g. UTF-8, UTF-16, etc) can be used?
Does it support normalization?
Note
This task is a bit unusual in that it encourages general discussion rather than clever coding.
See also
Unicode variable names
Terminal control/Display an extended character
| #Kotlin | Kotlin | // version 1.1.2
fun main(args: Array<String>) {
val åäö = "as⃝df̅ ♥♦♣♠ 頰"
println(åäö)
} |
http://rosettacode.org/wiki/Twin_primes | Twin primes | Twin primes are pairs of natural numbers (P1 and P2) that satisfy the following:
P1 and P2 are primes
P1 + 2 = P2
Task
Write a program that displays the number of pairs of twin primes that can be found under a user-specified number
(P1 < user-specified number & P2 < user-specified number).
Extension
Find all twin prime pairs under 100000, 10000000 and 1000000000.
What is the time complexity of the program? Are there ways to reduce computation time?
Examples
> Search Size: 100
> 8 twin prime pairs.
> Search Size: 1000
> 35 twin prime pairs.
Also see
The OEIS entry: A001097: Twin primes.
The OEIS entry: A167874: The number of distinct primes < 10^n which are members of twin-prime pairs.
The OEIS entry: A077800: List of twin primes {p, p+2}, with repetition.
The OEIS entry: A007508: Number of twin prime pairs below 10^n.
| #ALGOL_68 | ALGOL 68 | BEGIN
# count twin primes (where p and p - 2 are prime) #
PR heap=128M PR # set heap memory size for Algol 68G #
# sieve of Eratosthenes: sets s[i] to TRUE if i is a prime, FALSE otherwise #
PROC sieve = ( REF[]BOOL s )VOID:
BEGIN
FOR i TO UPB s DO s[ i ] := TRUE OD;
s[ 1 ] := FALSE;
FOR i FROM 2 TO ENTIER sqrt( UPB s ) DO
IF s[ i ] THEN FOR p FROM i * i BY i TO UPB s DO s[ p ] := FALSE OD FI
OD
END # sieve # ;
# find the maximum number to search for twin primes #
INT max;
print( ( "Maximum: " ) );
read( ( max, newline ) );
INT max number = max;
# construct a sieve of primes up to the maximum number #
[ 1 : max number ]BOOL primes;
sieve( primes );
# count the twin primes #
# note 2 cannot be one of the primes in a twin prime pair, so we start at 3 #
INT twin count := 0;
FOR p FROM 3 BY 2 TO max number - 1 DO IF primes[ p ] AND primes[ p - 2 ] THEN twin count +:= 1 FI OD;
print( ( "twin prime pairs below ", whole( max number, 0 ), ": ", whole( twin count, 0 ), newline ) )
END |
http://rosettacode.org/wiki/Unprimeable_numbers | Unprimeable numbers | Definitions
As used here, all unprimeable numbers (positive integers) are always expressed in base ten.
───── Definition from OEIS ─────:
Unprimeable numbers are composite numbers that always remain composite when a single decimal digit of the number is changed.
───── Definition from Wiktionary (referenced from Adam Spencer's book) ─────:
(arithmetic) that cannot be turned into a prime number by changing just one of its digits to any other
digit. (sic)
Unprimeable numbers are also spelled: unprimable.
All one─ and two─digit numbers can be turned into primes by changing a single decimal digit.
Examples
190 isn't unprimeable, because by changing the zero digit into a three yields 193, which is a prime.
The number 200 is unprimeable, since none of the numbers 201, 202, 203, ··· 209 are
prime, and all the other numbers obtained by changing a single digit to
produce 100, 300, 400, ··· 900, or 210, 220, 230, ··· 290 which are all even.
It is valid to change 189 into 089 by changing the 1 (one) into
a 0 (zero), which then the leading zero can be removed, and then treated as if
the "new" number is 89.
Task
show the first 35 unprimeable numbers (horizontally, on one line, preferably with a title)
show the 600th unprimeable number
(optional) show the lowest unprimeable number ending in a specific decimal digit (0, 1, 2, 3, 4, 5, 6, 7, 8, 9)
(optional) use commas in the numbers where appropriate
Show all output here, on this page.
Also see
the OEIS entry: A118118 (unprimeable)
with some useful counts to compare unprimeable number
the Wiktionary entry (reference from below): (arithmetic definition) unprimeable
from the Adam Spencer book (page 200): Adam Spencer's World of Numbers (Xoum Publishing)
| #J | J |
NB. replace concatenates at various ranks and in boxes to avoid fill
NB. the curtailed prefixes (}:\) with all of 0..9 (i.10) with the beheaded suffixes (}.\.)
NB. under the antibase 10 representation (10&#.inv)
replace=: ([: ; <@}:\ ,"1 L:_1 ([: < (i.10) ,"0 1 }.)\.)&.(10&#.inv)
NB. primable tests if one of the replacements is prime
primable=: (1 e. 1 p: replace)&>
unprimable=: -.@:primable
assert 0 1 -: unprimable 193 200
|
http://rosettacode.org/wiki/Unicode_variable_names | Unicode variable names | Task
Describe, and give a pointer to documentation on your languages use of characters beyond those of the ASCII character set in the naming of variables.
Show how to:
Set a variable with a name including the 'Δ', (delta character), to 1
Increment it
Print its value.
Related task
Case-sensitivity of identifiers
| #M2000_Interpreter | M2000 Interpreter |
Δ=1
Δ++
Print Δ
ᾩ=3
Print ᾩ**2=ᾩ^2, ᾩ^2-1=8
Τύπωσε ᾩ**2=ᾩ^2, ᾩ^2-1=8 ' this is Print statement too
Print ᾡ=3
जावास्क्रिप्ट=100
जावास्क्रिप्ट++
Print "जावास्क्रिप्ट=";जावास्क्रिप्ट
ĦĔĽĻŎ$="hello"
Print ĦĔĽĻŎ$+ħĕľļŏ$="hellohello"
〱〱〱〱$="too less"
Print Left$(〱〱〱〱$, 3)="too"
c͓͈̃͂̋̈̆̽h̥̪͕ͣ͛̊aͨͣ̍͞ơ̱͔̖͖̑̽ș̻̥ͬ̃̈ͩ =100 : Print "c͓͈̃͂̋̈̆̽h̥̪͕ͣ͛̊aͨͣ̍͞ơ̱͔̖͖̑̽ș̻̥ͬ̃̈ͩ ="; c͓͈̃͂̋̈̆̽h̥̪͕ͣ͛̊aͨͣ̍͞ơ̱͔̖͖̑̽ș̻̥ͬ̃̈ͩ
|
http://rosettacode.org/wiki/Unicode_variable_names | Unicode variable names | Task
Describe, and give a pointer to documentation on your languages use of characters beyond those of the ASCII character set in the naming of variables.
Show how to:
Set a variable with a name including the 'Δ', (delta character), to 1
Increment it
Print its value.
Related task
Case-sensitivity of identifiers
| #Mathematica.2FWolfram_Language | Mathematica/Wolfram Language | Δ = 1;
Δ++;
Print[Δ] |
http://rosettacode.org/wiki/Unicode_variable_names | Unicode variable names | Task
Describe, and give a pointer to documentation on your languages use of characters beyond those of the ASCII character set in the naming of variables.
Show how to:
Set a variable with a name including the 'Δ', (delta character), to 1
Increment it
Print its value.
Related task
Case-sensitivity of identifiers
| #Nemerle | Nemerle | using System.Console;
module UnicodeVar
{
Main() : void
{
mutable Δ = 1;
Δ++;
WriteLine($"Δ = $Δ");
}
} |
http://rosettacode.org/wiki/Unicode_variable_names | Unicode variable names | Task
Describe, and give a pointer to documentation on your languages use of characters beyond those of the ASCII character set in the naming of variables.
Show how to:
Set a variable with a name including the 'Δ', (delta character), to 1
Increment it
Print its value.
Related task
Case-sensitivity of identifiers
| #NetRexx | NetRexx | /* NetRexx */
options replace format comments java crossref symbols nobinary
upperΔ = 1
Δupper = upperΔ
lowerδ = 2
δlower = lowerδ
say upperΔ '+' Δupper '= \-'
upperΔ = upperΔ + Δupper
say upperΔ
say lowerδ '+' δlower '= \-'
lowerδ = lowerδ + δlower
say lowerδ
say
-- Unicode works with the NetRexx built-in functions
Υππερ = '\u0391'.sequence('\u03a1') || '\u03a3'.sequence('\u03a9') -- ΑΒΓΔΕΖΗΘΙΚΛΜΝΞΟΠΡΣΤΥΦΧΨΩ
Λοωερ = '\u03b1'.sequence('\u03c1') || '\u03c3'.sequence('\u03c9') -- αβγδεζηθικλμνξοπρστυφχψω
say Υππερ'.Lower =' Υππερ.lower()
say Λοωερ'.Upper =' Λοωερ.upper()
say
-- Note: Even with unicode characters NetRexx variables are case-insensitive
numeric digits 12
δ = 20.0
π = Math.PI
θ = Π * Δ
σ = Θ ** 2 / (Π * 4) -- == Π * (Δ / 2) ** 2
say 'Π =' π', diameter =' δ', circumference =' Θ', area =' Σ
return
|
http://rosettacode.org/wiki/Unbias_a_random_generator | Unbias a random generator |
P
1
{\displaystyle P_{1}}
P
0
{\displaystyle P_{0}}
P
1
{\displaystyle P_{1}}
P
0
{\displaystyle P_{0}}
P
0
{\displaystyle P_{0}}
P
1
{\displaystyle P_{1}}
Task details
Use your language's random number generator to create a function/method/subroutine/... randN that returns a one or a zero, but with one occurring, on average, 1 out of N times, where N is an integer from the range 3 to 6 inclusive.
Create a function unbiased that uses only randN as its source of randomness to become an unbiased generator of random ones and zeroes.
For N over its range, generate and show counts of the outputs of randN and unbiased(randN).
The actual unbiasing should be done by generating two numbers at a time from randN and only returning a 1 or 0 if they are different. As long as you always return the first number or always return the second number, the probabilities discussed above should take over the biased probability of randN.
This task is an implementation of Von Neumann debiasing, first described in a 1951 paper.
| #F.23 | F# | open System
let random = Random()
let randN = random.Next >> (=)0 >> Convert.ToInt32
let rec unbiased n =
let a = randN n
if a <> randN n then a else unbiased n
[<EntryPoint>]
let main argv =
let n = if argv.Length > 0 then UInt32.Parse(argv.[0]) |> int else 100000
for b = 3 to 6 do
let cb = ref 0
let cu = ref 0
for i = 1 to n do
cb := !cb + randN b
cu := !cu + unbiased b
printfn "%d: %5.2f%% %5.2f%%"
b (100. * float !cb / float n) (100. * float !cu / float n)
0 |
http://rosettacode.org/wiki/Untouchable_numbers | Untouchable numbers | Definitions
Untouchable numbers are also known as nonaliquot numbers.
An untouchable number is a positive integer that cannot be expressed as the sum of all the proper divisors of any positive integer. (From Wikipedia)
The sum of all the proper divisors is also known as the aliquot sum.
An untouchable are those numbers that are not in the image of the aliquot sum function. (From Wikipedia)
Untouchable numbers: impossible values for the sum of all aliquot parts function. (From OEIS: The On-line Encyclopedia of Integer Sequences®)
An untouchable number is a positive integer that is not the sum of the proper divisors of any number. (From MathWorld™)
Observations and conjectures
All untouchable numbers > 5 are composite numbers.
No untouchable number is perfect.
No untouchable number is sociable.
No untouchable number is a Mersenne prime.
No untouchable number is one more than a prime number, since if p is prime, then
the sum of the proper divisors of p2 is p + 1.
No untouchable number is three more than an odd prime number, since if p is an odd prime, then the
sum of the proper divisors of 2p is p + 3.
The number 5 is believed to be the only odd untouchable number, but this has not been proven: it would follow from a
slightly stronger version of the Goldbach's conjecture, since the sum of the
proper divisors of pq (with p, q being
distinct primes) is 1 + p + q.
There are infinitely many untouchable numbers, a fact that was proven
by Paul Erdős.
According to Chen & Zhao, their natural density is at least d > 0.06.
Task
show (in a grid format) all untouchable numbers ≤ 2,000.
show (for the above) the count of untouchable numbers.
show the count of untouchable numbers from unity up to (inclusive):
10
100
1,000
10,000
100,000
... or as high as is you think is practical.
all output is to be shown here, on this page.
See also
Wolfram MathWorld: untouchable number.
OEIS: A005114 untouchable numbers.
OEIS: a list of all untouchable numbers below 100,000 (inclusive).
Wikipedia: untouchable number.
Wikipedia: Goldbach's conjecture.
| #Wren | Wren | import "/math" for Int, Nums
import "/seq" for Lst
import "/fmt" for Fmt
var sieve = Fn.new { |n|
n = n + 1
var s = List.filled(n+1, false)
for (i in 0..n) {
var sum = Nums.sum(Int.properDivisors(i))
if (sum <= n) s[sum] = true
}
return s
}
var limit = 1e5
var c = Int.primeSieve(limit, false)
var s = sieve.call(14 * limit)
var untouchable = [2, 5]
var n = 6
while (n <= limit) {
if (!s[n] && c[n-1] && c[n-3]) untouchable.add(n)
n = n + 2
}
System.print("List of untouchable numbers <= 2,000:")
for (chunk in Lst.chunks(untouchable.where { |n| n <= 2000 }.toList, 10)) {
Fmt.print("$,6d", chunk)
}
System.print()
Fmt.print("$,6d untouchable numbers were found <= 2,000", untouchable.count { |n| n <= 2000 })
var p = 10
var count = 0
for (n in untouchable) {
count = count + 1
if (n > p) {
Fmt.print("$,6d untouchable numbers were found <= $,7d", count-1, p)
p = p * 10
if (p == limit) break
}
}
Fmt.print("$,6d untouchable numbers were found <= $,d", untouchable.count, limit) |
http://rosettacode.org/wiki/Two_bullet_roulette | Two bullet roulette | The following is supposedly a question given to mathematics graduates seeking jobs on Wall Street:
A revolver handgun has a revolving cylinder with six chambers for bullets.
It is loaded with the following procedure:
1. Check the first chamber to the right of the trigger for a bullet. If a bullet
is seen, the cylinder is rotated one chamber clockwise and the next chamber
checked until an empty chamber is found.
2. A cartridge containing a bullet is placed in the empty chamber.
3. The cylinder is then rotated one chamber clockwise.
To randomize the cylinder's position, the cylinder is spun, which causes the cylinder to take
a random position from 1 to 6 chamber rotations clockwise from its starting position.
When the trigger is pulled the gun will fire if there is a bullet in position 0, which is just
counterclockwise from the loading position.
The gun is unloaded by removing all cartridges from the cylinder.
According to the legend, a suicidal Russian imperial military officer plays a game of Russian
roulette by putting two bullets in a six-chamber cylinder and pulls the trigger twice.
If the gun fires with a trigger pull, this is considered a successful suicide.
The cylinder is always spun before the first shot, but it may or may not be spun after putting
in the first bullet and may or may not be spun after taking the first shot.
Which of the following situations produces the highest probability of suicide?
A. Spinning the cylinder after loading the first bullet, and spinning again after the first shot.
B. Spinning the cylinder after loading the first bullet only.
C. Spinning the cylinder after firing the first shot only.
D. Not spinning the cylinder either after loading the first bullet or after the first shot.
E. The probability is the same for all cases.
Task
Run a repeated simulation of each of the above scenario, calculating the percentage of suicide with a randomization of the four spinning, loading and firing order scenarios.
Show the results as a percentage of deaths for each type of scenario.
The hand calculated probabilities are 5/9, 7/12, 5/9, and 1/2. A correct program should produce results close enough to those to allow a correct response to the interview question.
Reference
Youtube video on the Russian 1895 Nagant revolver [[1]]
| #C | C | #include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
static int nextInt(int size) {
return rand() % size;
}
static bool cylinder[6];
static void rshift() {
bool t = cylinder[5];
int i;
for (i = 4; i >= 0; i--) {
cylinder[i + 1] = cylinder[i];
}
cylinder[0] = t;
}
static void unload() {
int i;
for (i = 0; i < 6; i++) {
cylinder[i] = false;
}
}
static void load() {
while (cylinder[0]) {
rshift();
}
cylinder[0] = true;
rshift();
}
static void spin() {
int lim = nextInt(6) + 1;
int i;
for (i = 1; i < lim; i++) {
rshift();
}
}
static bool fire() {
bool shot = cylinder[0];
rshift();
return shot;
}
static int method(const char *s) {
unload();
for (; *s != '\0'; s++) {
switch (*s) {
case 'L':
load();
break;
case 'S':
spin();
break;
case 'F':
if (fire()) {
return 1;
}
break;
}
}
return 0;
}
static void append(char *out, const char *txt) {
if (*out != '\0') {
strcat(out, ", ");
}
strcat(out, txt);
}
static void mstring(const char *s, char *out) {
for (; *s != '\0'; s++) {
switch (*s) {
case 'L':
append(out, "load");
break;
case 'S':
append(out, "spin");
break;
case 'F':
append(out, "fire");
break;
}
}
}
static void test(char *src) {
char buffer[41] = "";
const int tests = 100000;
int sum = 0;
int t;
double pc;
for (t = 0; t < tests; t++) {
sum += method(src);
}
mstring(src, buffer);
pc = 100.0 * sum / tests;
printf("%-40s produces %6.3f%% deaths.\n", buffer, pc);
}
int main() {
srand(time(0));
test("LSLSFSF");
test("LSLSFF");
test("LLSFSF");
test("LLSFF");
return 0;
} |
http://rosettacode.org/wiki/Unix/ls | Unix/ls | Task
Write a program that will list everything in the current folder, similar to:
the Unix utility “ls” [1] or
the Windows terminal command “DIR”
The output must be sorted, but printing extended details and producing multi-column output is not required.
Example output
For the list of paths:
/foo/bar
/foo/bar/1
/foo/bar/2
/foo/bar/a
/foo/bar/b
When the program is executed in `/foo`, it should print:
bar
and when the program is executed in `/foo/bar`, it should print:
1
2
a
b
| #Kotlin | Kotlin | // Version 1.2.41
import java.io.File
fun ls(directory: String) {
val d = File(directory)
if (!d.isDirectory) {
println("$directory is not a directory")
return
}
d.listFiles().map { it.name }
.sortedBy { it.toLowerCase() } // case insensitive
.forEach { println(it) }
}
fun main(args: Array<String>) {
ls(".") // list files in current directory, say
} |
http://rosettacode.org/wiki/Unix/ls | Unix/ls | Task
Write a program that will list everything in the current folder, similar to:
the Unix utility “ls” [1] or
the Windows terminal command “DIR”
The output must be sorted, but printing extended details and producing multi-column output is not required.
Example output
For the list of paths:
/foo/bar
/foo/bar/1
/foo/bar/2
/foo/bar/a
/foo/bar/b
When the program is executed in `/foo`, it should print:
bar
and when the program is executed in `/foo/bar`, it should print:
1
2
a
b
| #Ksh | Ksh |
#!/bin/ksh
# List everything in the current folder (sorted), similar to `ls`
# # Variables:
#
targetDir=${1:-/tmp/foo}
######
# main #
######
cd ${targetDir}
for obj in *; do
print ${obj}
done
|
http://rosettacode.org/wiki/Vector_products | Vector products | A vector is defined as having three dimensions as being represented by an ordered collection of three numbers: (X, Y, Z).
If you imagine a graph with the x and y axis being at right angles to each other and having a third, z axis coming out of the page, then a triplet of numbers, (X, Y, Z) would represent a point in the region, and a vector from the origin to the point.
Given the vectors:
A = (a1, a2, a3)
B = (b1, b2, b3)
C = (c1, c2, c3)
then the following common vector products are defined:
The dot product (a scalar quantity)
A • B = a1b1 + a2b2 + a3b3
The cross product (a vector quantity)
A x B = (a2b3 - a3b2, a3b1 - a1b3, a1b2 - a2b1)
The scalar triple product (a scalar quantity)
A • (B x C)
The vector triple product (a vector quantity)
A x (B x C)
Task
Given the three vectors:
a = ( 3, 4, 5)
b = ( 4, 3, 5)
c = (-5, -12, -13)
Create a named function/subroutine/method to compute the dot product of two vectors.
Create a function to compute the cross product of two vectors.
Optionally create a function to compute the scalar triple product of three vectors.
Optionally create a function to compute the vector triple product of three vectors.
Compute and display: a • b
Compute and display: a x b
Compute and display: a • (b x c), the scalar triple product.
Compute and display: a x (b x c), the vector triple product.
References
A starting page on Wolfram MathWorld is Vector Multiplication .
Wikipedia dot product.
Wikipedia cross product.
Wikipedia triple product.
Related tasks
Dot product
Quaternion type
| #Scala | Scala | case class Vector3D(x:Double, y:Double, z:Double) {
def dot(v:Vector3D):Double=x*v.x + y*v.y + z*v.z;
def cross(v:Vector3D)=Vector3D(y*v.z - z*v.y, z*v.x - x*v.z, x*v.y - y*v.x)
def scalarTriple(v1:Vector3D, v2:Vector3D)=this dot (v1 cross v2)
def vectorTriple(v1:Vector3D, v2:Vector3D)=this cross (v1 cross v2)
}
object VectorTest {
def main(args:Array[String])={
val a=Vector3D(3,4,5)
val b=Vector3D(4,3,5)
val c=Vector3D(-5,-12,-13)
println(" a . b : " + (a dot b))
println(" a x b : " + (a cross b))
println("a . (b x c) : " + (a scalarTriple(b, c)))
println("a x (b x c) : " + (a vectorTriple(b, c)))
}
} |
http://rosettacode.org/wiki/User_input/Text | User input/Text | User input/Text is part of Short Circuit's Console Program Basics selection.
Task
Input a string and the integer 75000 from the text console.
See also: User input/Graphical
| #XLISP | XLISP | (display "Enter a string: ")
(define s (read-line))
(display "Yes, ")
(write s)
(display " is a string.") ;; no need to verify, because READ-LINE has to return a string
(newline)
(display "Now enter the integer 75000: ")
(define n (read))
(display
(cond
((not (integerp n))
"That's not even an integer." )
((/= n 75000)
"That is not the integer 75000." )
(t
"Yes, that is the integer 75000." ) ) ) |
http://rosettacode.org/wiki/User_input/Text | User input/Text | User input/Text is part of Short Circuit's Console Program Basics selection.
Task
Input a string and the integer 75000 from the text console.
See also: User input/Graphical
| #XPL0 | XPL0 | string 0; \use zero-terminated strings, instead of MSb terminated
include c:\cxpl\codes;
int I;
char Name(128); \the keyboard buffer limits input to 128 characters
[Text(0, "What's your name? ");
I:= 0;
loop [Name(I):= ChIn(0); \buffered keyboard input
if Name(I) = $0D\CR\ then quit; \Carriage Return = Enter key
I:= I+1;
];
Name(I):= 0; \terminate string
Text(0, "Howdy "); Text(0, Name); Text(0, "! Now please enter ^"75000^": ");
IntOut(0, IntIn(0)); CrLf(0); \echo the number
] |
http://rosettacode.org/wiki/Undefined_values | Undefined values | #Phix | Phix | object x
procedure test()
if object(x) then
puts(1,"x is an object\n")
else
puts(1,"x is unassigned\n")
end if
end procedure
test()
x = 1
test()
|
|
http://rosettacode.org/wiki/Undefined_values | Undefined values | #PHP | PHP | <?php
// Check to see whether it is defined
if (!isset($var))
echo "var is undefined at first check\n";
// Give it a value
$var = "Chocolate";
// Check to see whether it is defined after we gave it the
// value "Chocolate"
if (!isset($var))
echo "var is undefined at second check\n";
// Give the variable an undefined value.
unset($var);
// Check to see whether it is defined after we've explicitly
// given it an undefined value.
if (!isset($var))
echo "var is undefined at third check\n";
// Give the variable a value of 42
$var = 42;
// Check to see whether the it is defined after we've given it
// the value 42.
if (!isset($var))
echo "var is undefined at fourth check\n";
// Because most of the output is conditional, this serves as
// a clear indicator that the program has run to completion.
echo "Done\n";
?> |
|
http://rosettacode.org/wiki/Unicode_strings | Unicode strings | As the world gets smaller each day, internationalization becomes more and more important. For handling multiple languages, Unicode is your best friend.
It is a very capable tool, but also quite complex compared to older single- and double-byte character encodings.
How well prepared is your programming language for Unicode?
Task
Discuss and demonstrate its unicode awareness and capabilities.
Some suggested topics:
How easy is it to present Unicode strings in source code?
Can Unicode literals be written directly, or be part of identifiers/keywords/etc?
How well can the language communicate with the rest of the world?
Is it good at input/output with Unicode?
Is it convenient to manipulate Unicode strings in the language?
How broad/deep does the language support Unicode?
What encodings (e.g. UTF-8, UTF-16, etc) can be used?
Does it support normalization?
Note
This task is a bit unusual in that it encourages general discussion rather than clever coding.
See also
Unicode variable names
Terminal control/Display an extended character
| #langur | langur | q:any"any code points here" |
http://rosettacode.org/wiki/Unicode_strings | Unicode strings | As the world gets smaller each day, internationalization becomes more and more important. For handling multiple languages, Unicode is your best friend.
It is a very capable tool, but also quite complex compared to older single- and double-byte character encodings.
How well prepared is your programming language for Unicode?
Task
Discuss and demonstrate its unicode awareness and capabilities.
Some suggested topics:
How easy is it to present Unicode strings in source code?
Can Unicode literals be written directly, or be part of identifiers/keywords/etc?
How well can the language communicate with the rest of the world?
Is it good at input/output with Unicode?
Is it convenient to manipulate Unicode strings in the language?
How broad/deep does the language support Unicode?
What encodings (e.g. UTF-8, UTF-16, etc) can be used?
Does it support normalization?
Note
This task is a bit unusual in that it encourages general discussion rather than clever coding.
See also
Unicode variable names
Terminal control/Display an extended character
| #Lasso | Lasso | local(unicode = '♥♦♣♠')
#unicode -> append('\u9830')
#unicode
'<br />'
#unicode -> get (2)
'<br />'
#unicode -> get (4) -> integer |
http://rosettacode.org/wiki/Unicode_strings | Unicode strings | As the world gets smaller each day, internationalization becomes more and more important. For handling multiple languages, Unicode is your best friend.
It is a very capable tool, but also quite complex compared to older single- and double-byte character encodings.
How well prepared is your programming language for Unicode?
Task
Discuss and demonstrate its unicode awareness and capabilities.
Some suggested topics:
How easy is it to present Unicode strings in source code?
Can Unicode literals be written directly, or be part of identifiers/keywords/etc?
How well can the language communicate with the rest of the world?
Is it good at input/output with Unicode?
Is it convenient to manipulate Unicode strings in the language?
How broad/deep does the language support Unicode?
What encodings (e.g. UTF-8, UTF-16, etc) can be used?
Does it support normalization?
Note
This task is a bit unusual in that it encourages general discussion rather than clever coding.
See also
Unicode variable names
Terminal control/Display an extended character
| #LFE | LFE |
> (set encoded (binary ("åäö ð" utf8)))
#B(195 165 195 164 195 182 32 195 176)
|
http://rosettacode.org/wiki/Twin_primes | Twin primes | Twin primes are pairs of natural numbers (P1 and P2) that satisfy the following:
P1 and P2 are primes
P1 + 2 = P2
Task
Write a program that displays the number of pairs of twin primes that can be found under a user-specified number
(P1 < user-specified number & P2 < user-specified number).
Extension
Find all twin prime pairs under 100000, 10000000 and 1000000000.
What is the time complexity of the program? Are there ways to reduce computation time?
Examples
> Search Size: 100
> 8 twin prime pairs.
> Search Size: 1000
> 35 twin prime pairs.
Also see
The OEIS entry: A001097: Twin primes.
The OEIS entry: A167874: The number of distinct primes < 10^n which are members of twin-prime pairs.
The OEIS entry: A077800: List of twin primes {p, p+2}, with repetition.
The OEIS entry: A007508: Number of twin prime pairs below 10^n.
| #Arturo | Arturo | pairsOfPrimes: function [upperLim][
count: 0
j: 0
k: 1
i: 0
while [i=<upperLim][
i: (6 * k) - 1
j: i + 2
if and? [prime? i] [prime? j] [
count: count + 1
]
k: k + 1
]
return count + 1
]
ToNum: 10
while [ToNum =< 1000000][
x: pairsOfPrimes ToNum
print ["From 2 to" ToNum ": there are" x "pairs of twin primes"]
ToNum: ToNum * 10
] |
http://rosettacode.org/wiki/Twin_primes | Twin primes | Twin primes are pairs of natural numbers (P1 and P2) that satisfy the following:
P1 and P2 are primes
P1 + 2 = P2
Task
Write a program that displays the number of pairs of twin primes that can be found under a user-specified number
(P1 < user-specified number & P2 < user-specified number).
Extension
Find all twin prime pairs under 100000, 10000000 and 1000000000.
What is the time complexity of the program? Are there ways to reduce computation time?
Examples
> Search Size: 100
> 8 twin prime pairs.
> Search Size: 1000
> 35 twin prime pairs.
Also see
The OEIS entry: A001097: Twin primes.
The OEIS entry: A167874: The number of distinct primes < 10^n which are members of twin-prime pairs.
The OEIS entry: A077800: List of twin primes {p, p+2}, with repetition.
The OEIS entry: A007508: Number of twin prime pairs below 10^n.
| #AWK | AWK |
# syntax: GAWK -f TWIN_PRIMES.AWK
BEGIN {
n = 1
for (i=1; i<=6; i++) {
n *= 10
printf("twin prime pairs < %8s : %d\n",n,count_twin_primes(n))
}
exit(0)
}
function count_twin_primes(limit, count,i,p1,p2,p3) {
p1 = 0
p2 = p3 = 1
for (i=5; i<=limit; i++) {
p3 = p2
p2 = p1
p1 = is_prime(i)
if (p3 && p1) {
count++
}
}
return(count)
}
function is_prime(x, i) {
if (x <= 1) {
return(0)
}
for (i=2; i<=int(sqrt(x)); i++) {
if (x % i == 0) {
return(0)
}
}
return(1)
}
|
http://rosettacode.org/wiki/Unprimeable_numbers | Unprimeable numbers | Definitions
As used here, all unprimeable numbers (positive integers) are always expressed in base ten.
───── Definition from OEIS ─────:
Unprimeable numbers are composite numbers that always remain composite when a single decimal digit of the number is changed.
───── Definition from Wiktionary (referenced from Adam Spencer's book) ─────:
(arithmetic) that cannot be turned into a prime number by changing just one of its digits to any other
digit. (sic)
Unprimeable numbers are also spelled: unprimable.
All one─ and two─digit numbers can be turned into primes by changing a single decimal digit.
Examples
190 isn't unprimeable, because by changing the zero digit into a three yields 193, which is a prime.
The number 200 is unprimeable, since none of the numbers 201, 202, 203, ··· 209 are
prime, and all the other numbers obtained by changing a single digit to
produce 100, 300, 400, ··· 900, or 210, 220, 230, ··· 290 which are all even.
It is valid to change 189 into 089 by changing the 1 (one) into
a 0 (zero), which then the leading zero can be removed, and then treated as if
the "new" number is 89.
Task
show the first 35 unprimeable numbers (horizontally, on one line, preferably with a title)
show the 600th unprimeable number
(optional) show the lowest unprimeable number ending in a specific decimal digit (0, 1, 2, 3, 4, 5, 6, 7, 8, 9)
(optional) use commas in the numbers where appropriate
Show all output here, on this page.
Also see
the OEIS entry: A118118 (unprimeable)
with some useful counts to compare unprimeable number
the Wiktionary entry (reference from below): (arithmetic definition) unprimeable
from the Adam Spencer book (page 200): Adam Spencer's World of Numbers (Xoum Publishing)
| #Java | Java |
public class UnprimeableNumbers {
private static int MAX = 10_000_000;
private static boolean[] primes = new boolean[MAX];
public static void main(String[] args) {
sieve();
System.out.println("First 35 unprimeable numbers:");
displayUnprimeableNumbers(35);
int n = 600;
System.out.printf("%nThe %dth unprimeable number = %,d%n%n", n, nthUnprimeableNumber(n));
int[] lowest = genLowest();
System.out.println("Least unprimeable number that ends in:");
for ( int i = 0 ; i <= 9 ; i++ ) {
System.out.printf(" %d is %,d%n", i, lowest[i]);
}
}
private static int[] genLowest() {
int[] lowest = new int[10];
int count = 0;
int test = 1;
while ( count < 10 ) {
test++;
if ( unPrimable(test) && lowest[test % 10] == 0 ) {
lowest[test % 10] = test;
count++;
}
}
return lowest;
}
private static int nthUnprimeableNumber(int maxCount) {
int test = 1;
int count = 0;
int result = 0;
while ( count < maxCount ) {
test++;
if ( unPrimable(test) ) {
count++;
result = test;
}
}
return result;
}
private static void displayUnprimeableNumbers(int maxCount) {
int test = 1;
int count = 0;
while ( count < maxCount ) {
test++;
if ( unPrimable(test) ) {
count++;
System.out.printf("%d ", test);
}
}
System.out.println();
}
private static boolean unPrimable(int test) {
if ( primes[test] ) {
return false;
}
String s = test + "";
for ( int i = 0 ; i < s.length() ; i++ ) {
for ( int j = 0 ; j <= 9 ; j++ ) {
if ( primes[Integer.parseInt(replace(s, i, j))] ) {
return false;
}
}
}
return true;
}
private static String replace(String str, int position, int value) {
char[] sChar = str.toCharArray();
sChar[position] = (char) value;
return str.substring(0, position) + value + str.substring(position + 1);
}
private static final void sieve() {
// primes
for ( int i = 2 ; i < MAX ; i++ ) {
primes[i] = true;
}
for ( int i = 2 ; i < MAX ; i++ ) {
if ( primes[i] ) {
for ( int j = 2*i ; j < MAX ; j += i ) {
primes[j] = false;
}
}
}
}
}
|
http://rosettacode.org/wiki/Unicode_variable_names | Unicode variable names | Task
Describe, and give a pointer to documentation on your languages use of characters beyond those of the ASCII character set in the naming of variables.
Show how to:
Set a variable with a name including the 'Δ', (delta character), to 1
Increment it
Print its value.
Related task
Case-sensitivity of identifiers
| #Nim | Nim | var Δ = 1
inc Δ
echo Δ |
http://rosettacode.org/wiki/Unicode_variable_names | Unicode variable names | Task
Describe, and give a pointer to documentation on your languages use of characters beyond those of the ASCII character set in the naming of variables.
Show how to:
Set a variable with a name including the 'Δ', (delta character), to 1
Increment it
Print its value.
Related task
Case-sensitivity of identifiers
| #Objeck | Objeck |
class Test {
function : Main(args : String[]) ~ Nil {
Δ := 1;
π := 3.141592;
你好 := "hello";
Δ += 1;
Δ->PrintLine();
}
}
|
http://rosettacode.org/wiki/Unicode_variable_names | Unicode variable names | Task
Describe, and give a pointer to documentation on your languages use of characters beyond those of the ASCII character set in the naming of variables.
Show how to:
Set a variable with a name including the 'Δ', (delta character), to 1
Increment it
Print its value.
Related task
Case-sensitivity of identifiers
| #Ol | Ol |
(define Δ 1)
(define Δ (+ Δ 1))
(print Δ)
|
http://rosettacode.org/wiki/Unbias_a_random_generator | Unbias a random generator |
P
1
{\displaystyle P_{1}}
P
0
{\displaystyle P_{0}}
P
1
{\displaystyle P_{1}}
P
0
{\displaystyle P_{0}}
P
0
{\displaystyle P_{0}}
P
1
{\displaystyle P_{1}}
Task details
Use your language's random number generator to create a function/method/subroutine/... randN that returns a one or a zero, but with one occurring, on average, 1 out of N times, where N is an integer from the range 3 to 6 inclusive.
Create a function unbiased that uses only randN as its source of randomness to become an unbiased generator of random ones and zeroes.
For N over its range, generate and show counts of the outputs of randN and unbiased(randN).
The actual unbiasing should be done by generating two numbers at a time from randN and only returning a 1 or 0 if they are different. As long as you always return the first number or always return the second number, the probabilities discussed above should take over the biased probability of randN.
This task is an implementation of Von Neumann debiasing, first described in a 1951 paper.
| #Factor | Factor | USING: formatting kernel math math.ranges random sequences ;
IN: rosetta-code.unbias
: randN ( n -- m ) random zero? 1 0 ? ;
: unbiased ( n -- m )
dup [ randN ] dup bi 2dup = not
[ drop nip ] [ 2drop unbiased ] if ;
: test-generator ( quot -- x )
[ 1,000,000 dup ] dip replicate sum 100 * swap / ; inline
: main ( -- )
3 6 [a,b] [
dup [ randN ] [ unbiased ] bi-curry
[ test-generator ] bi@ "%d: %.2f%% %.2f%%\n" printf
] each ;
MAIN: main |
http://rosettacode.org/wiki/Unbias_a_random_generator | Unbias a random generator |
P
1
{\displaystyle P_{1}}
P
0
{\displaystyle P_{0}}
P
1
{\displaystyle P_{1}}
P
0
{\displaystyle P_{0}}
P
0
{\displaystyle P_{0}}
P
1
{\displaystyle P_{1}}
Task details
Use your language's random number generator to create a function/method/subroutine/... randN that returns a one or a zero, but with one occurring, on average, 1 out of N times, where N is an integer from the range 3 to 6 inclusive.
Create a function unbiased that uses only randN as its source of randomness to become an unbiased generator of random ones and zeroes.
For N over its range, generate and show counts of the outputs of randN and unbiased(randN).
The actual unbiasing should be done by generating two numbers at a time from randN and only returning a 1 or 0 if they are different. As long as you always return the first number or always return the second number, the probabilities discussed above should take over the biased probability of randN.
This task is an implementation of Von Neumann debiasing, first described in a 1951 paper.
| #Fortran | Fortran | program Bias_Unbias
implicit none
integer, parameter :: samples = 1000000
integer :: i, j
integer :: c1, c2, rand
do i = 3, 6
c1 = 0
c2 = 0
do j = 1, samples
rand = bias(i)
if (rand == 1) c1 = c1 + 1
rand = unbias(i)
if (rand == 1) c2 = c2 + 1
end do
write(*, "(i2,a,f8.3,a,f8.3,a)") i, ":", real(c1) * 100.0 / real(samples), &
"%", real(c2) * 100.0 / real(samples), "%"
end do
contains
function bias(n)
integer :: bias
integer, intent(in) :: n
real :: r
call random_number(r)
if (r > 1 / real(n)) then
bias = 0
else
bias = 1
end if
end function
function unbias(n)
integer :: unbias
integer, intent(in) :: n
integer :: a, b
do
a = bias(n)
b = bias(n)
if (a /= b) exit
end do
unbias = a
end function
end program |
http://rosettacode.org/wiki/Two_bullet_roulette | Two bullet roulette | The following is supposedly a question given to mathematics graduates seeking jobs on Wall Street:
A revolver handgun has a revolving cylinder with six chambers for bullets.
It is loaded with the following procedure:
1. Check the first chamber to the right of the trigger for a bullet. If a bullet
is seen, the cylinder is rotated one chamber clockwise and the next chamber
checked until an empty chamber is found.
2. A cartridge containing a bullet is placed in the empty chamber.
3. The cylinder is then rotated one chamber clockwise.
To randomize the cylinder's position, the cylinder is spun, which causes the cylinder to take
a random position from 1 to 6 chamber rotations clockwise from its starting position.
When the trigger is pulled the gun will fire if there is a bullet in position 0, which is just
counterclockwise from the loading position.
The gun is unloaded by removing all cartridges from the cylinder.
According to the legend, a suicidal Russian imperial military officer plays a game of Russian
roulette by putting two bullets in a six-chamber cylinder and pulls the trigger twice.
If the gun fires with a trigger pull, this is considered a successful suicide.
The cylinder is always spun before the first shot, but it may or may not be spun after putting
in the first bullet and may or may not be spun after taking the first shot.
Which of the following situations produces the highest probability of suicide?
A. Spinning the cylinder after loading the first bullet, and spinning again after the first shot.
B. Spinning the cylinder after loading the first bullet only.
C. Spinning the cylinder after firing the first shot only.
D. Not spinning the cylinder either after loading the first bullet or after the first shot.
E. The probability is the same for all cases.
Task
Run a repeated simulation of each of the above scenario, calculating the percentage of suicide with a randomization of the four spinning, loading and firing order scenarios.
Show the results as a percentage of deaths for each type of scenario.
The hand calculated probabilities are 5/9, 7/12, 5/9, and 1/2. A correct program should produce results close enough to those to allow a correct response to the interview question.
Reference
Youtube video on the Russian 1895 Nagant revolver [[1]]
| #C.2B.2B | C++ | #include <array>
#include <iomanip>
#include <iostream>
#include <random>
#include <sstream>
class Roulette {
private:
std::array<bool, 6> cylinder;
std::mt19937 gen;
std::uniform_int_distribution<> distrib;
int next_int() {
return distrib(gen);
}
void rshift() {
std::rotate(cylinder.begin(), cylinder.begin() + 1, cylinder.end());
}
void unload() {
std::fill(cylinder.begin(), cylinder.end(), false);
}
void load() {
while (cylinder[0]) {
rshift();
}
cylinder[0] = true;
rshift();
}
void spin() {
int lim = next_int();
for (int i = 1; i < lim; i++) {
rshift();
}
}
bool fire() {
auto shot = cylinder[0];
rshift();
return shot;
}
public:
Roulette() {
std::random_device rd;
gen = std::mt19937(rd());
distrib = std::uniform_int_distribution<>(1, 6);
unload();
}
int method(const std::string &s) {
unload();
for (auto c : s) {
switch (c) {
case 'L':
load();
break;
case 'S':
spin();
break;
case 'F':
if (fire()) {
return 1;
}
break;
}
}
return 0;
}
};
std::string mstring(const std::string &s) {
std::stringstream ss;
bool first = true;
auto append = [&ss, &first](const std::string s) {
if (first) {
first = false;
} else {
ss << ", ";
}
ss << s;
};
for (auto c : s) {
switch (c) {
case 'L':
append("load");
break;
case 'S':
append("spin");
break;
case 'F':
append("fire");
break;
}
}
return ss.str();
}
void test(const std::string &src) {
const int tests = 100000;
int sum = 0;
Roulette r;
for (int t = 0; t < tests; t++) {
sum += r.method(src);
}
double pc = 100.0 * sum / tests;
std::cout << std::left << std::setw(40) << mstring(src) << " produces " << pc << "% deaths.\n";
}
int main() {
test("LSLSFSF");
test("LSLSFF");
test("LLSFSF");
test("LLSFF");
return 0;
} |
http://rosettacode.org/wiki/Unix/ls | Unix/ls | Task
Write a program that will list everything in the current folder, similar to:
the Unix utility “ls” [1] or
the Windows terminal command “DIR”
The output must be sorted, but printing extended details and producing multi-column output is not required.
Example output
For the list of paths:
/foo/bar
/foo/bar/1
/foo/bar/2
/foo/bar/a
/foo/bar/b
When the program is executed in `/foo`, it should print:
bar
and when the program is executed in `/foo/bar`, it should print:
1
2
a
b
| #LiveCode | LiveCode | set the defaultFolder to "/foo"
put the folders & the files
set the defaultFolder to "/foo/bar"
put the folders & the files |
http://rosettacode.org/wiki/Unix/ls | Unix/ls | Task
Write a program that will list everything in the current folder, similar to:
the Unix utility “ls” [1] or
the Windows terminal command “DIR”
The output must be sorted, but printing extended details and producing multi-column output is not required.
Example output
For the list of paths:
/foo/bar
/foo/bar/1
/foo/bar/2
/foo/bar/a
/foo/bar/b
When the program is executed in `/foo`, it should print:
bar
and when the program is executed in `/foo/bar`, it should print:
1
2
a
b
| #Lua | Lua | require("lfs")
for file in lfs.dir(".") do print(file) end |
http://rosettacode.org/wiki/Unix/ls | Unix/ls | Task
Write a program that will list everything in the current folder, similar to:
the Unix utility “ls” [1] or
the Windows terminal command “DIR”
The output must be sorted, but printing extended details and producing multi-column output is not required.
Example output
For the list of paths:
/foo/bar
/foo/bar/1
/foo/bar/2
/foo/bar/a
/foo/bar/b
When the program is executed in `/foo`, it should print:
bar
and when the program is executed in `/foo/bar`, it should print:
1
2
a
b
| #Mathematica.2FWolfram_Language | Mathematica/Wolfram Language | Column[FileNames[]] |
http://rosettacode.org/wiki/Vector_products | Vector products | A vector is defined as having three dimensions as being represented by an ordered collection of three numbers: (X, Y, Z).
If you imagine a graph with the x and y axis being at right angles to each other and having a third, z axis coming out of the page, then a triplet of numbers, (X, Y, Z) would represent a point in the region, and a vector from the origin to the point.
Given the vectors:
A = (a1, a2, a3)
B = (b1, b2, b3)
C = (c1, c2, c3)
then the following common vector products are defined:
The dot product (a scalar quantity)
A • B = a1b1 + a2b2 + a3b3
The cross product (a vector quantity)
A x B = (a2b3 - a3b2, a3b1 - a1b3, a1b2 - a2b1)
The scalar triple product (a scalar quantity)
A • (B x C)
The vector triple product (a vector quantity)
A x (B x C)
Task
Given the three vectors:
a = ( 3, 4, 5)
b = ( 4, 3, 5)
c = (-5, -12, -13)
Create a named function/subroutine/method to compute the dot product of two vectors.
Create a function to compute the cross product of two vectors.
Optionally create a function to compute the scalar triple product of three vectors.
Optionally create a function to compute the vector triple product of three vectors.
Compute and display: a • b
Compute and display: a x b
Compute and display: a • (b x c), the scalar triple product.
Compute and display: a x (b x c), the vector triple product.
References
A starting page on Wolfram MathWorld is Vector Multiplication .
Wikipedia dot product.
Wikipedia cross product.
Wikipedia triple product.
Related tasks
Dot product
Quaternion type
| #Scheme | Scheme | (define (dot-product A B)
(apply + (map * (vector->list A) (vector->list B))))
(define (cross-product A B)
(define len (vector-length A))
(define xp (make-vector (vector-length A) #f))
(let loop ((n 0))
(vector-set! xp n (-
(* (vector-ref A (modulo (+ n 1) len))
(vector-ref B (modulo (+ n 2) len)))
(* (vector-ref A (modulo (+ n 2) len))
(vector-ref B (modulo (+ n 1) len)))))
(if (eqv? len (+ n 1))
xp
(loop (+ n 1)))))
(define (scalar-triple-product A B C)
(dot-product A (cross-product B C)))
(define (vector-triple-product A B C)
(cross-product A (cross-product B C)))
(define A #( 3 4 5))
(define B #(4 3 5))
(define C #(-5 -12 -13))
(display "A = ")(display A)(newline)
(display "B = ")(display B)(newline)
(display "C = ")(display C)(newline)
(newline)
(display "A . B = ")(display (dot-product A B))(newline)
(display "A x B = ")(display (cross-product A B))(newline)
(display "A . B x C = ")(display (scalar-triple-product A B C))(newline)
(display "A x B x C = ") (display (vector-triple-product A B C))(newline) |
http://rosettacode.org/wiki/User_input/Text | User input/Text | User input/Text is part of Short Circuit's Console Program Basics selection.
Task
Input a string and the integer 75000 from the text console.
See also: User input/Graphical
| #zkl | zkl | str:=ask("Gimmie a string: ");
n:=ask("Type 75000: ").toInt(); |
http://rosettacode.org/wiki/User_input/Text | User input/Text | User input/Text is part of Short Circuit's Console Program Basics selection.
Task
Input a string and the integer 75000 from the text console.
See also: User input/Graphical
| #ZX_Spectrum_Basic | ZX Spectrum Basic | 10 INPUT "Enter a string:"; s$
20 INPUT "Enter a number: "; n |
http://rosettacode.org/wiki/Undefined_values | Undefined values | #PicoLisp | PicoLisp | : (myfoo 3 4)
!? (myfoo 3 4)
myfoo -- Undefined
? |
|
http://rosettacode.org/wiki/Undefined_values | Undefined values | #Pike | Pike |
> zero_type(UNDEFINED);
Result: 1
> mapping bar = ([ "foo":"hello" ]);
> zero_type(bar->foo);
Result: 0
> zero_type(bar->baz);
Result: 1
> bar->baz=UNDEFINED;
Result: 0
> zero_type(bar->baz);
Result: 0
|
|
http://rosettacode.org/wiki/Unicode_strings | Unicode strings | As the world gets smaller each day, internationalization becomes more and more important. For handling multiple languages, Unicode is your best friend.
It is a very capable tool, but also quite complex compared to older single- and double-byte character encodings.
How well prepared is your programming language for Unicode?
Task
Discuss and demonstrate its unicode awareness and capabilities.
Some suggested topics:
How easy is it to present Unicode strings in source code?
Can Unicode literals be written directly, or be part of identifiers/keywords/etc?
How well can the language communicate with the rest of the world?
Is it good at input/output with Unicode?
Is it convenient to manipulate Unicode strings in the language?
How broad/deep does the language support Unicode?
What encodings (e.g. UTF-8, UTF-16, etc) can be used?
Does it support normalization?
Note
This task is a bit unusual in that it encourages general discussion rather than clever coding.
See also
Unicode variable names
Terminal control/Display an extended character
| #Lingo | Lingo | put _system.getInstalledCharSets()
-- ["big5", "cp1026", "cp866", "ebcdic-cp-us", "gb2312", "ibm437", "ibm737",
"ibm775", "ibm850", "ibm852", "ibm857", "ibm861", "ibm869", "iso-8859-1",
"iso-8859-15", "iso-8859-2", "iso-8859-4", "iso-8859-5", "iso-8859-7",
"iso-8859-9", "johab", "koi8-r", "koi8-u", "ks_c_5601-1987", "macintosh",
"shift_jis", "us-ascii", "utf-16", "utf-16be", "utf-7", "utf-8", "windows-1250",
"windows-1251", "windows-1252", "windows-1253", "windows-1254", "windows-1255",
"windows-1256", "windows-1257", "windows-1258", "windows-874",
"x-ebcdic-greekmodern", "x-mac-ce", "x-mac-cyrillic", "x-mac-greek",
"x-mac-icelandic", "x-mac-turkish"] |
http://rosettacode.org/wiki/Unicode_strings | Unicode strings | As the world gets smaller each day, internationalization becomes more and more important. For handling multiple languages, Unicode is your best friend.
It is a very capable tool, but also quite complex compared to older single- and double-byte character encodings.
How well prepared is your programming language for Unicode?
Task
Discuss and demonstrate its unicode awareness and capabilities.
Some suggested topics:
How easy is it to present Unicode strings in source code?
Can Unicode literals be written directly, or be part of identifiers/keywords/etc?
How well can the language communicate with the rest of the world?
Is it good at input/output with Unicode?
Is it convenient to manipulate Unicode strings in the language?
How broad/deep does the language support Unicode?
What encodings (e.g. UTF-8, UTF-16, etc) can be used?
Does it support normalization?
Note
This task is a bit unusual in that it encourages general discussion rather than clever coding.
See also
Unicode variable names
Terminal control/Display an extended character
| #Locomotive_Basic | Locomotive Basic | 10 CLS:DEFINT a-z
20 ' define German umlauts as in Latin-1
30 SYMBOL AFTER 196
40 SYMBOL 196,&66,&18,&3C,&66,&7E,&66,&66,&0
50 SYMBOL 214,&C6,&0,&7C,&C6,&C6,&C6,&7C,&0
60 SYMBOL 220,&66,&0,&66,&66,&66,&66,&3C,&0
70 SYMBOL 228,&6C,&0,&78,&C,&7C,&CC,&76,&0
80 SYMBOL 246,&66,&0,&0,&3C,&66,&66,&3C,&0
90 SYMBOL 252,&66,&0,&0,&66,&66,&66,&3E,&0
100 SYMBOL 223,&38,&6C,&6C,&78,&6C,&78,&60,&0
110 ' print string
120 READ h
130 IF h=0 THEN 180
140 IF (h AND &X11100000)=&X11000000 THEN uc=(h AND &X11111)*2^6:GOTO 120
150 IF (h AND &X11000000)=&X10000000 THEN uc=uc+(h AND &X111111):h=uc
160 PRINT CHR$(h);
170 GOTO 120
180 PRINT
190 END
200 ' zero-terminated UTF-8 string
210 DATA &48,&C3,&A4,&6C,&6C,&C3,&B6,&20,&4C,&C3,&BC,&64,&77,&69,&67,&2E,&20,&C3,&84,&C3,&96,&C3,&9C
220 DATA &20,&C3,&A4,&C3,&B6,&C3,&BC,&20,&56,&69,&65,&6C,&65,&20,&47,&72,&C3,&BC,&C3,&9F,&65,&21,&00 |
http://rosettacode.org/wiki/Twin_primes | Twin primes | Twin primes are pairs of natural numbers (P1 and P2) that satisfy the following:
P1 and P2 are primes
P1 + 2 = P2
Task
Write a program that displays the number of pairs of twin primes that can be found under a user-specified number
(P1 < user-specified number & P2 < user-specified number).
Extension
Find all twin prime pairs under 100000, 10000000 and 1000000000.
What is the time complexity of the program? Are there ways to reduce computation time?
Examples
> Search Size: 100
> 8 twin prime pairs.
> Search Size: 1000
> 35 twin prime pairs.
Also see
The OEIS entry: A001097: Twin primes.
The OEIS entry: A167874: The number of distinct primes < 10^n which are members of twin-prime pairs.
The OEIS entry: A077800: List of twin primes {p, p+2}, with repetition.
The OEIS entry: A007508: Number of twin prime pairs below 10^n.
| #BASIC256 | BASIC256 |
function isPrime(v)
if v < 2 then return False
if v mod 2 = 0 then return v = 2
if v mod 3 = 0 then return v = 3
d = 5
while d * d <= v
if v mod d = 0 then return False else d += 2
end while
return True
end function
function paresDePrimos(limite)
p1 = 0
p2 = 1
p3 = 1
cont = 0
for i = 5 to limite
p3 = p2
p2 = p1
p1 = isPrime(i)
if (p3 and p1) then cont += 1
next i
return cont
end function
n = 1
for i = 1 to 6
n = n * 10
print "pares de primos gemelos por debajo de < "; n; " : "; paresDePrimos(n)
next i
end
|
http://rosettacode.org/wiki/Twin_primes | Twin primes | Twin primes are pairs of natural numbers (P1 and P2) that satisfy the following:
P1 and P2 are primes
P1 + 2 = P2
Task
Write a program that displays the number of pairs of twin primes that can be found under a user-specified number
(P1 < user-specified number & P2 < user-specified number).
Extension
Find all twin prime pairs under 100000, 10000000 and 1000000000.
What is the time complexity of the program? Are there ways to reduce computation time?
Examples
> Search Size: 100
> 8 twin prime pairs.
> Search Size: 1000
> 35 twin prime pairs.
Also see
The OEIS entry: A001097: Twin primes.
The OEIS entry: A167874: The number of distinct primes < 10^n which are members of twin-prime pairs.
The OEIS entry: A077800: List of twin primes {p, p+2}, with repetition.
The OEIS entry: A007508: Number of twin prime pairs below 10^n.
| #C | C | #include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
bool isPrime(int64_t n) {
int64_t i;
if (n < 2) return false;
if (n % 2 == 0) return n == 2;
if (n % 3 == 0) return n == 3;
if (n % 5 == 0) return n == 5;
if (n % 7 == 0) return n == 7;
if (n % 11 == 0) return n == 11;
if (n % 13 == 0) return n == 13;
if (n % 17 == 0) return n == 17;
if (n % 19 == 0) return n == 19;
for (i = 23; i * i <= n; i += 2) {
if (n % i == 0) return false;
}
return true;
}
int countTwinPrimes(int limit) {
int count = 0;
// 2 3 4
int64_t p3 = true, p2 = true, p1 = false;
int64_t i;
for (i = 5; i <= limit; i++) {
p3 = p2;
p2 = p1;
p1 = isPrime(i);
if (p3 && p1) {
count++;
}
}
return count;
}
void test(int limit) {
int count = countTwinPrimes(limit);
printf("Number of twin prime pairs less than %d is %d\n", limit, count);
}
int main() {
test(10);
test(100);
test(1000);
test(10000);
test(100000);
test(1000000);
test(10000000);
test(100000000);
return 0;
} |
http://rosettacode.org/wiki/Unprimeable_numbers | Unprimeable numbers | Definitions
As used here, all unprimeable numbers (positive integers) are always expressed in base ten.
───── Definition from OEIS ─────:
Unprimeable numbers are composite numbers that always remain composite when a single decimal digit of the number is changed.
───── Definition from Wiktionary (referenced from Adam Spencer's book) ─────:
(arithmetic) that cannot be turned into a prime number by changing just one of its digits to any other
digit. (sic)
Unprimeable numbers are also spelled: unprimable.
All one─ and two─digit numbers can be turned into primes by changing a single decimal digit.
Examples
190 isn't unprimeable, because by changing the zero digit into a three yields 193, which is a prime.
The number 200 is unprimeable, since none of the numbers 201, 202, 203, ··· 209 are
prime, and all the other numbers obtained by changing a single digit to
produce 100, 300, 400, ··· 900, or 210, 220, 230, ··· 290 which are all even.
It is valid to change 189 into 089 by changing the 1 (one) into
a 0 (zero), which then the leading zero can be removed, and then treated as if
the "new" number is 89.
Task
show the first 35 unprimeable numbers (horizontally, on one line, preferably with a title)
show the 600th unprimeable number
(optional) show the lowest unprimeable number ending in a specific decimal digit (0, 1, 2, 3, 4, 5, 6, 7, 8, 9)
(optional) use commas in the numbers where appropriate
Show all output here, on this page.
Also see
the OEIS entry: A118118 (unprimeable)
with some useful counts to compare unprimeable number
the Wiktionary entry (reference from below): (arithmetic definition) unprimeable
from the Adam Spencer book (page 200): Adam Spencer's World of Numbers (Xoum Publishing)
| #JavaScript | JavaScript |
Number.prototype.isPrime = function() {
let i = 2, num = this;
if (num == 0 || num == 1) return false;
if (num == 2) return true;
while (i <= Math.ceil(Math.sqrt(num))) {
if (num % i == 0) return false;
i++;
}
return true;
}
|
http://rosettacode.org/wiki/Unicode_variable_names | Unicode variable names | Task
Describe, and give a pointer to documentation on your languages use of characters beyond those of the ASCII character set in the naming of variables.
Show how to:
Set a variable with a name including the 'Δ', (delta character), to 1
Increment it
Print its value.
Related task
Case-sensitivity of identifiers
| #PARI.2FGP | PARI/GP | <@ LETVARLIT>Δ|1</@>
<@ ACTICRVAR>Δ</@>
<@ SAYVAR>Δ</@> |
http://rosettacode.org/wiki/Unicode_variable_names | Unicode variable names | Task
Describe, and give a pointer to documentation on your languages use of characters beyond those of the ASCII character set in the naming of variables.
Show how to:
Set a variable with a name including the 'Δ', (delta character), to 1
Increment it
Print its value.
Related task
Case-sensitivity of identifiers
| #Peloton | Peloton | <@ LETVARLIT>Δ|1</@>
<@ ACTICRVAR>Δ</@>
<@ SAYVAR>Δ</@> |
http://rosettacode.org/wiki/Unicode_variable_names | Unicode variable names | Task
Describe, and give a pointer to documentation on your languages use of characters beyond those of the ASCII character set in the naming of variables.
Show how to:
Set a variable with a name including the 'Δ', (delta character), to 1
Increment it
Print its value.
Related task
Case-sensitivity of identifiers
| #Perl | Perl | use utf8;
my $Δ = 1;
$Δ++;
print $Δ, "\n"; |
http://rosettacode.org/wiki/Unicode_variable_names | Unicode variable names | Task
Describe, and give a pointer to documentation on your languages use of characters beyond those of the ASCII character set in the naming of variables.
Show how to:
Set a variable with a name including the 'Δ', (delta character), to 1
Increment it
Print its value.
Related task
Case-sensitivity of identifiers
| #Phix | Phix | with javascript_semantics
integer Δ = 1
Δ += 1
?Δ
|
http://rosettacode.org/wiki/Unbias_a_random_generator | Unbias a random generator |
P
1
{\displaystyle P_{1}}
P
0
{\displaystyle P_{0}}
P
1
{\displaystyle P_{1}}
P
0
{\displaystyle P_{0}}
P
0
{\displaystyle P_{0}}
P
1
{\displaystyle P_{1}}
Task details
Use your language's random number generator to create a function/method/subroutine/... randN that returns a one or a zero, but with one occurring, on average, 1 out of N times, where N is an integer from the range 3 to 6 inclusive.
Create a function unbiased that uses only randN as its source of randomness to become an unbiased generator of random ones and zeroes.
For N over its range, generate and show counts of the outputs of randN and unbiased(randN).
The actual unbiasing should be done by generating two numbers at a time from randN and only returning a 1 or 0 if they are different. As long as you always return the first number or always return the second number, the probabilities discussed above should take over the biased probability of randN.
This task is an implementation of Von Neumann debiasing, first described in a 1951 paper.
| #FreeBASIC | FreeBASIC |
Function randN (n As Ubyte) As Ubyte
If Int(Rnd * n) + 1 <> 1 Then Return 0 Else Return 1
End Function
Function unbiased (n As Ubyte) As Ubyte
Dim As Ubyte a, b
Do
a = randN (n)
b = randN (n)
Loop Until a <> b
Return a
End Function
Const count = 100000
Dim x As Ubyte
Randomize Timer
Print "Resultados de n";Chr(163);!"meros aleatorios sesgados e imparciales\n"
For n As Ubyte = 3 To 6
Dim As Integer b_count(1)
Dim As Integer u_count(1)
For m As Integer = 1 To count
x = randN (n)
b_count(x) += 1
x = unbiased (n)
u_count(x) += 1
Next m
Print "N ="; n
Print " Biased =>", "#0="; Str(b_count(0)), "#1="; Str(b_count(1)),
Print Using "ratio = ##.##%"; (b_count(1) / count * 100)
Print "Unbiased =>", "#0="; Str(u_count(0)), "#1="; Str(u_count(1)),
Print Using "ratio = ##.##%"; (u_count(1) / count * 100)
Next n
Sleep
|
http://rosettacode.org/wiki/Two_bullet_roulette | Two bullet roulette | The following is supposedly a question given to mathematics graduates seeking jobs on Wall Street:
A revolver handgun has a revolving cylinder with six chambers for bullets.
It is loaded with the following procedure:
1. Check the first chamber to the right of the trigger for a bullet. If a bullet
is seen, the cylinder is rotated one chamber clockwise and the next chamber
checked until an empty chamber is found.
2. A cartridge containing a bullet is placed in the empty chamber.
3. The cylinder is then rotated one chamber clockwise.
To randomize the cylinder's position, the cylinder is spun, which causes the cylinder to take
a random position from 1 to 6 chamber rotations clockwise from its starting position.
When the trigger is pulled the gun will fire if there is a bullet in position 0, which is just
counterclockwise from the loading position.
The gun is unloaded by removing all cartridges from the cylinder.
According to the legend, a suicidal Russian imperial military officer plays a game of Russian
roulette by putting two bullets in a six-chamber cylinder and pulls the trigger twice.
If the gun fires with a trigger pull, this is considered a successful suicide.
The cylinder is always spun before the first shot, but it may or may not be spun after putting
in the first bullet and may or may not be spun after taking the first shot.
Which of the following situations produces the highest probability of suicide?
A. Spinning the cylinder after loading the first bullet, and spinning again after the first shot.
B. Spinning the cylinder after loading the first bullet only.
C. Spinning the cylinder after firing the first shot only.
D. Not spinning the cylinder either after loading the first bullet or after the first shot.
E. The probability is the same for all cases.
Task
Run a repeated simulation of each of the above scenario, calculating the percentage of suicide with a randomization of the four spinning, loading and firing order scenarios.
Show the results as a percentage of deaths for each type of scenario.
The hand calculated probabilities are 5/9, 7/12, 5/9, and 1/2. A correct program should produce results close enough to those to allow a correct response to the interview question.
Reference
Youtube video on the Russian 1895 Nagant revolver [[1]]
| #EasyLang | EasyLang | len cyl[] 6
func rshift . .
h = cyl[5]
for i = 5 downto 1
cyl[i] = cyl[i - 1]
.
cyl[0] = h
.
func unload . .
for i range 6
cyl[i] = 0
.
.
func load . .
while cyl[0] = 1
call rshift
.
cyl[0] = 1
call rshift
.
func spin . .
lim = random 6 + 1
for i = 1 to lim - 1
call rshift
.
.
func fire . shot .
shot = cyl[0]
call rshift
.
func method m[] . shot .
call unload
shot = 0
for m in m[]
if m = 0
call load
elif m = 1
call spin
elif m = 2
call fire shot
if shot = 1
break 1
.
.
.
.
method$[] = [ "load" "spin" "fire" ]
func test m[] . .
n = 100000
for i range n
call method m[] shot
sum += shot
.
for m in m[]
write method$[m] & " "
.
print "-> " & 100 * sum / n & "% deaths"
.
call test [ 0 1 0 1 2 1 2 ]
call test [ 0 1 0 1 2 2 ]
call test [ 0 0 1 2 1 2 ]
call test [ 0 0 1 2 2 ] |
http://rosettacode.org/wiki/Two_bullet_roulette | Two bullet roulette | The following is supposedly a question given to mathematics graduates seeking jobs on Wall Street:
A revolver handgun has a revolving cylinder with six chambers for bullets.
It is loaded with the following procedure:
1. Check the first chamber to the right of the trigger for a bullet. If a bullet
is seen, the cylinder is rotated one chamber clockwise and the next chamber
checked until an empty chamber is found.
2. A cartridge containing a bullet is placed in the empty chamber.
3. The cylinder is then rotated one chamber clockwise.
To randomize the cylinder's position, the cylinder is spun, which causes the cylinder to take
a random position from 1 to 6 chamber rotations clockwise from its starting position.
When the trigger is pulled the gun will fire if there is a bullet in position 0, which is just
counterclockwise from the loading position.
The gun is unloaded by removing all cartridges from the cylinder.
According to the legend, a suicidal Russian imperial military officer plays a game of Russian
roulette by putting two bullets in a six-chamber cylinder and pulls the trigger twice.
If the gun fires with a trigger pull, this is considered a successful suicide.
The cylinder is always spun before the first shot, but it may or may not be spun after putting
in the first bullet and may or may not be spun after taking the first shot.
Which of the following situations produces the highest probability of suicide?
A. Spinning the cylinder after loading the first bullet, and spinning again after the first shot.
B. Spinning the cylinder after loading the first bullet only.
C. Spinning the cylinder after firing the first shot only.
D. Not spinning the cylinder either after loading the first bullet or after the first shot.
E. The probability is the same for all cases.
Task
Run a repeated simulation of each of the above scenario, calculating the percentage of suicide with a randomization of the four spinning, loading and firing order scenarios.
Show the results as a percentage of deaths for each type of scenario.
The hand calculated probabilities are 5/9, 7/12, 5/9, and 1/2. A correct program should produce results close enough to those to allow a correct response to the interview question.
Reference
Youtube video on the Russian 1895 Nagant revolver [[1]]
| #Factor | Factor | USING: accessors assocs circular formatting fry kernel literals
math random sequences ;
IN: rosetta-code.roulette
CONSTANT: cyl $[ { f f f f f f } <circular> ]
: cylinder ( -- seq ) cyl [ drop f ] map! ;
: load ( seq -- seq' )
0 over nth [ dup rotate-circular ] when
t 0 rot [ set-nth ] [ rotate-circular ] [ ] tri ;
: spin ( seq -- seq' ) [ 6 random 1 + + ] change-start ;
: fire ( seq -- ? seq' )
[ 0 swap nth ] [ rotate-circular ] [ ] tri ;
: LSLSFSF ( -- ? ) cylinder load spin load spin fire spin fire drop or ;
: LSLSFF ( -- ? ) cylinder load spin load spin fire fire drop or ;
: LLSFSF ( -- ? ) cylinder load load spin fire spin fire drop or ;
: LLSFF ( -- ? ) cylinder load load spin fire fire drop or ;
: percent ( ... n quot: ( ... -- ... ? ) -- ... x )
0 -rot '[ _ call( -- ? ) 1 0 ? + ] [ times ] keepd /f 100 * ; inline
: run-test ( description quot -- )
100,000 swap percent
"Method <%s> produces %.3f%% deaths.\n" printf ;
: main ( -- )
{
{ "load, spin, load, spin, fire, spin, fire" [ LSLSFSF ] }
{ "load, spin, load, spin, fire, fire" [ LSLSFF ] }
{ "load, load, spin, fire, spin, fire" [ LLSFSF ] }
{ "load, load, spin, fire, fire" [ LLSFF ] }
} [ run-test ] assoc-each ;
MAIN: main |
http://rosettacode.org/wiki/Two_bullet_roulette | Two bullet roulette | The following is supposedly a question given to mathematics graduates seeking jobs on Wall Street:
A revolver handgun has a revolving cylinder with six chambers for bullets.
It is loaded with the following procedure:
1. Check the first chamber to the right of the trigger for a bullet. If a bullet
is seen, the cylinder is rotated one chamber clockwise and the next chamber
checked until an empty chamber is found.
2. A cartridge containing a bullet is placed in the empty chamber.
3. The cylinder is then rotated one chamber clockwise.
To randomize the cylinder's position, the cylinder is spun, which causes the cylinder to take
a random position from 1 to 6 chamber rotations clockwise from its starting position.
When the trigger is pulled the gun will fire if there is a bullet in position 0, which is just
counterclockwise from the loading position.
The gun is unloaded by removing all cartridges from the cylinder.
According to the legend, a suicidal Russian imperial military officer plays a game of Russian
roulette by putting two bullets in a six-chamber cylinder and pulls the trigger twice.
If the gun fires with a trigger pull, this is considered a successful suicide.
The cylinder is always spun before the first shot, but it may or may not be spun after putting
in the first bullet and may or may not be spun after taking the first shot.
Which of the following situations produces the highest probability of suicide?
A. Spinning the cylinder after loading the first bullet, and spinning again after the first shot.
B. Spinning the cylinder after loading the first bullet only.
C. Spinning the cylinder after firing the first shot only.
D. Not spinning the cylinder either after loading the first bullet or after the first shot.
E. The probability is the same for all cases.
Task
Run a repeated simulation of each of the above scenario, calculating the percentage of suicide with a randomization of the four spinning, loading and firing order scenarios.
Show the results as a percentage of deaths for each type of scenario.
The hand calculated probabilities are 5/9, 7/12, 5/9, and 1/2. A correct program should produce results close enough to those to allow a correct response to the interview question.
Reference
Youtube video on the Russian 1895 Nagant revolver [[1]]
| #Go | Go | package main
import (
"fmt"
"math/rand"
"strings"
"time"
)
var cylinder = [6]bool{}
func rshift() {
t := cylinder[5]
for i := 4; i >= 0; i-- {
cylinder[i+1] = cylinder[i]
}
cylinder[0] = t
}
func unload() {
for i := 0; i < 6; i++ {
cylinder[i] = false
}
}
func load() {
for cylinder[0] {
rshift()
}
cylinder[0] = true
rshift()
}
func spin() {
var lim = 1 + rand.Intn(6)
for i := 1; i < lim; i++ {
rshift()
}
}
func fire() bool {
shot := cylinder[0]
rshift()
return shot
}
func method(s string) int {
unload()
for _, c := range s {
switch c {
case 'L':
load()
case 'S':
spin()
case 'F':
if fire() {
return 1
}
}
}
return 0
}
func mstring(s string) string {
var l []string
for _, c := range s {
switch c {
case 'L':
l = append(l, "load")
case 'S':
l = append(l, "spin")
case 'F':
l = append(l, "fire")
}
}
return strings.Join(l, ", ")
}
func main() {
rand.Seed(time.Now().UnixNano())
tests := 100000
for _, m := range []string{"LSLSFSF", "LSLSFF", "LLSFSF", "LLSFF"} {
sum := 0
for t := 1; t <= tests; t++ {
sum += method(m)
}
pc := float64(sum) * 100 / float64(tests)
fmt.Printf("%-40s produces %6.3f%% deaths.\n", mstring(m), pc)
}
} |
http://rosettacode.org/wiki/Unix/ls | Unix/ls | Task
Write a program that will list everything in the current folder, similar to:
the Unix utility “ls” [1] or
the Windows terminal command “DIR”
The output must be sorted, but printing extended details and producing multi-column output is not required.
Example output
For the list of paths:
/foo/bar
/foo/bar/1
/foo/bar/2
/foo/bar/a
/foo/bar/b
When the program is executed in `/foo`, it should print:
bar
and when the program is executed in `/foo/bar`, it should print:
1
2
a
b
| #Nanoquery | Nanoquery | import Nanoquery.IO
import sort
fnames = sort(new(File).listDir("."))
for i in range(0, len(fnames) - 1)
println fnames[i]
end |
http://rosettacode.org/wiki/Unix/ls | Unix/ls | Task
Write a program that will list everything in the current folder, similar to:
the Unix utility “ls” [1] or
the Windows terminal command “DIR”
The output must be sorted, but printing extended details and producing multi-column output is not required.
Example output
For the list of paths:
/foo/bar
/foo/bar/1
/foo/bar/2
/foo/bar/a
/foo/bar/b
When the program is executed in `/foo`, it should print:
bar
and when the program is executed in `/foo/bar`, it should print:
1
2
a
b
| #Nim | Nim | from algorithm import sorted
from os import walkPattern
from sequtils import toSeq
for path in toSeq(walkPattern("*")).sorted:
echo path |
http://rosettacode.org/wiki/Unix/ls | Unix/ls | Task
Write a program that will list everything in the current folder, similar to:
the Unix utility “ls” [1] or
the Windows terminal command “DIR”
The output must be sorted, but printing extended details and producing multi-column output is not required.
Example output
For the list of paths:
/foo/bar
/foo/bar/1
/foo/bar/2
/foo/bar/a
/foo/bar/b
When the program is executed in `/foo`, it should print:
bar
and when the program is executed in `/foo/bar`, it should print:
1
2
a
b
| #Objeck | Objeck |
class Test {
function : Main(args : String[]) ~ Nil {
file_names := System.IO.File.Directory->List(".");
each(i : file_names) {
file_name := file_names[i];
if(System.IO.File.Directory->Exists(file_name)) {
file_name += '/';
};
file_name->PrintLine();
};
}
}
|
http://rosettacode.org/wiki/Vector_products | Vector products | A vector is defined as having three dimensions as being represented by an ordered collection of three numbers: (X, Y, Z).
If you imagine a graph with the x and y axis being at right angles to each other and having a third, z axis coming out of the page, then a triplet of numbers, (X, Y, Z) would represent a point in the region, and a vector from the origin to the point.
Given the vectors:
A = (a1, a2, a3)
B = (b1, b2, b3)
C = (c1, c2, c3)
then the following common vector products are defined:
The dot product (a scalar quantity)
A • B = a1b1 + a2b2 + a3b3
The cross product (a vector quantity)
A x B = (a2b3 - a3b2, a3b1 - a1b3, a1b2 - a2b1)
The scalar triple product (a scalar quantity)
A • (B x C)
The vector triple product (a vector quantity)
A x (B x C)
Task
Given the three vectors:
a = ( 3, 4, 5)
b = ( 4, 3, 5)
c = (-5, -12, -13)
Create a named function/subroutine/method to compute the dot product of two vectors.
Create a function to compute the cross product of two vectors.
Optionally create a function to compute the scalar triple product of three vectors.
Optionally create a function to compute the vector triple product of three vectors.
Compute and display: a • b
Compute and display: a x b
Compute and display: a • (b x c), the scalar triple product.
Compute and display: a x (b x c), the vector triple product.
References
A starting page on Wolfram MathWorld is Vector Multiplication .
Wikipedia dot product.
Wikipedia cross product.
Wikipedia triple product.
Related tasks
Dot product
Quaternion type
| #Seed7 | Seed7 | $ include "seed7_05.s7i";
include "float.s7i";
const type: vec3 is new struct
var float: x is 0.0;
var float: y is 0.0;
var float: z is 0.0;
end struct;
const func vec3: vec3 (in float: x, in float: y, in float: z) is func
result
var vec3: aVector is vec3.value;
begin
aVector.x := x;
aVector.y := y;
aVector.z := z;
end func;
$ syntax expr: .(). dot .() is -> 6;
const func float: (in vec3: a) dot (in vec3: b) is
return a.x*b.x + a.y*b.y + a.z*b.z;
$ syntax expr: .(). X .() is -> 6;
const func vec3: (in vec3: a) X (in vec3: b) is
return vec3(a.y*b.z - a.z*b.y,
a.z*b.x - a.x*b.z,
a.x*b.y - a.y*b.x);
const func string: str (in vec3: v) is
return "(" <& v.x <& ", " <& v.y <& ", " <& v.z <& ")";
enable_output(vec3);
const func float: scalarTriple (in vec3: a, in vec3: b, in vec3: c) is
return a dot (b X c);
const func vec3: vectorTriple (in vec3: a, in vec3: b, in vec3: c) is
return a X (b X c);
const proc: main is func
local
const vec3: a is vec3(3.0, 4.0, 5.0);
const vec3: b is vec3(4.0, 3.0, 5.0);
const vec3: c is vec3(-5.0, -12.0, -13.0);
begin
writeln("a = " <& a <& ", b = " <& b <& ", c = " <& c);
writeln("a . b = " <& a dot b);
writeln("a x b = " <& a X b);
writeln("a .(b x c) = " <& scalarTriple(a, b, c));
writeln("a x(b x c) = " <& vectorTriple(a, b, c));
end func; |
http://rosettacode.org/wiki/Undefined_values | Undefined values | #PowerShell | PowerShell |
if (Get-Variable -Name noSuchVariable -ErrorAction SilentlyContinue)
{
$true
}
else
{
$false
}
|
|
http://rosettacode.org/wiki/Undefined_values | Undefined values | #Prolog | Prolog | ?- var(Y).
true.
?- X = 4, var(X).
false.
?- nonvar(Y).
false.
?- X = 4, nonvar(X).
X = 4.
|
|
http://rosettacode.org/wiki/Unicode_strings | Unicode strings | As the world gets smaller each day, internationalization becomes more and more important. For handling multiple languages, Unicode is your best friend.
It is a very capable tool, but also quite complex compared to older single- and double-byte character encodings.
How well prepared is your programming language for Unicode?
Task
Discuss and demonstrate its unicode awareness and capabilities.
Some suggested topics:
How easy is it to present Unicode strings in source code?
Can Unicode literals be written directly, or be part of identifiers/keywords/etc?
How well can the language communicate with the rest of the world?
Is it good at input/output with Unicode?
Is it convenient to manipulate Unicode strings in the language?
How broad/deep does the language support Unicode?
What encodings (e.g. UTF-8, UTF-16, etc) can be used?
Does it support normalization?
Note
This task is a bit unusual in that it encourages general discussion rather than clever coding.
See also
Unicode variable names
Terminal control/Display an extended character
| #M2000_Interpreter | M2000 Interpreter |
Font "Arial"
Mode 32
' M2000 internal editor can display left to rigtht languages if text is in same line, and same color.
a$="لم أجد هذا الكتاب القديم"
' We can use console to display text, using proportional spacing
Print Part $(4), a$
Print
' We can display right to left using
' the legend statement which render text at a given
' graphic point, specify the font type and font size
' and optional:
' rotation angle, justification (1 for right,2 for center, 3 for left)
'quality (0 or non 0, which 0 no antialliasing)
' letter spacing in twips (not good for arabic language)
move 6000,6000
legend a$, "Arial", 32, pi/4, 2, 0
' Variables can use any unicode letter.
' Here we can't display it as in M2000 editor.
' in the editor we see at the left the variable name
' and at the right the value
القديم=10
Print القديم+1=11 ' true
|
http://rosettacode.org/wiki/Unicode_strings | Unicode strings | As the world gets smaller each day, internationalization becomes more and more important. For handling multiple languages, Unicode is your best friend.
It is a very capable tool, but also quite complex compared to older single- and double-byte character encodings.
How well prepared is your programming language for Unicode?
Task
Discuss and demonstrate its unicode awareness and capabilities.
Some suggested topics:
How easy is it to present Unicode strings in source code?
Can Unicode literals be written directly, or be part of identifiers/keywords/etc?
How well can the language communicate with the rest of the world?
Is it good at input/output with Unicode?
Is it convenient to manipulate Unicode strings in the language?
How broad/deep does the language support Unicode?
What encodings (e.g. UTF-8, UTF-16, etc) can be used?
Does it support normalization?
Note
This task is a bit unusual in that it encourages general discussion rather than clever coding.
See also
Unicode variable names
Terminal control/Display an extended character
| #Mathematica.2FWolfram_Language | Mathematica/Wolfram Language | {"AdobeStandard", "ASCII", "CP936", "CP949", "CP950", "Custom",
"EUC-JP", "EUC", "IBM-850", "ISO10646-1", "ISO8859-15", "ISO8859-1",
"ISO8859-2", "ISO8859-3", "ISO8859-4", "ISO8859-5", "ISO8859-6",
"ISO8859-7", "ISO8859-8", "ISO8859-9", "ISOLatin1", "ISOLatin2",
"ISOLatin3", "ISOLatin4", "ISOLatinCyrillic", "Klingon", "KOI8-R",
"MacintoshArabic", "MacintoshChineseSimplified",
"MacintoshChineseTraditional", "MacintoshCroatian",
"MacintoshCyrillic", "MacintoshGreek", "MacintoshHebrew",
"MacintoshIcelandic", "MacintoshKorean",
"MacintoshNonCyrillicSlavic", "MacintoshRomanian", "MacintoshRoman",
"MacintoshThai", "MacintoshTurkish", "MacintoshUkrainian", "Math1",
"Math2", "Math3", "Math4", "Math5", "Mathematica1", "Mathematica2",
"Mathematica3", "Mathematica4", "Mathematica5", "Mathematica6",
"Mathematica7", "PrintableASCII", "ShiftJIS", "Symbol", "Unicode",
"UTF8", "WindowsANSI", "WindowsBaltic", "WindowsCyrillic",
"WindowsEastEurope", "WindowsGreek", "WindowsThai", "WindowsTurkish",
"ZapfDingbats"} |
http://rosettacode.org/wiki/Unicode_strings | Unicode strings | As the world gets smaller each day, internationalization becomes more and more important. For handling multiple languages, Unicode is your best friend.
It is a very capable tool, but also quite complex compared to older single- and double-byte character encodings.
How well prepared is your programming language for Unicode?
Task
Discuss and demonstrate its unicode awareness and capabilities.
Some suggested topics:
How easy is it to present Unicode strings in source code?
Can Unicode literals be written directly, or be part of identifiers/keywords/etc?
How well can the language communicate with the rest of the world?
Is it good at input/output with Unicode?
Is it convenient to manipulate Unicode strings in the language?
How broad/deep does the language support Unicode?
What encodings (e.g. UTF-8, UTF-16, etc) can be used?
Does it support normalization?
Note
This task is a bit unusual in that it encourages general discussion rather than clever coding.
See also
Unicode variable names
Terminal control/Display an extended character
| #Nemerle | Nemerle | use utf8; |
http://rosettacode.org/wiki/Twin_primes | Twin primes | Twin primes are pairs of natural numbers (P1 and P2) that satisfy the following:
P1 and P2 are primes
P1 + 2 = P2
Task
Write a program that displays the number of pairs of twin primes that can be found under a user-specified number
(P1 < user-specified number & P2 < user-specified number).
Extension
Find all twin prime pairs under 100000, 10000000 and 1000000000.
What is the time complexity of the program? Are there ways to reduce computation time?
Examples
> Search Size: 100
> 8 twin prime pairs.
> Search Size: 1000
> 35 twin prime pairs.
Also see
The OEIS entry: A001097: Twin primes.
The OEIS entry: A167874: The number of distinct primes < 10^n which are members of twin-prime pairs.
The OEIS entry: A077800: List of twin primes {p, p+2}, with repetition.
The OEIS entry: A007508: Number of twin prime pairs below 10^n.
| #C.2B.2B | C++ | #include <cstdint>
#include <iostream>
#include <string>
#include <primesieve.hpp>
void print_twin_prime_count(long long limit) {
std::cout << "Number of twin prime pairs less than " << limit
<< " is " << (limit > 0 ? primesieve::count_twins(0, limit - 1) : 0) << '\n';
}
int main(int argc, char** argv) {
std::cout.imbue(std::locale(""));
if (argc > 1) {
// print number of twin prime pairs less than limits specified
// on the command line
for (int i = 1; i < argc; ++i) {
try {
print_twin_prime_count(std::stoll(argv[i]));
} catch (const std::exception& ex) {
std::cerr << "Cannot parse limit from '" << argv[i] << "'\n";
}
}
} else {
// if no limit was specified then show the number of twin prime
// pairs less than powers of 10 up to 100 billion
uint64_t limit = 10;
for (int power = 1; power < 12; ++power, limit *= 10)
print_twin_prime_count(limit);
}
return 0;
} |
http://rosettacode.org/wiki/Unprimeable_numbers | Unprimeable numbers | Definitions
As used here, all unprimeable numbers (positive integers) are always expressed in base ten.
───── Definition from OEIS ─────:
Unprimeable numbers are composite numbers that always remain composite when a single decimal digit of the number is changed.
───── Definition from Wiktionary (referenced from Adam Spencer's book) ─────:
(arithmetic) that cannot be turned into a prime number by changing just one of its digits to any other
digit. (sic)
Unprimeable numbers are also spelled: unprimable.
All one─ and two─digit numbers can be turned into primes by changing a single decimal digit.
Examples
190 isn't unprimeable, because by changing the zero digit into a three yields 193, which is a prime.
The number 200 is unprimeable, since none of the numbers 201, 202, 203, ··· 209 are
prime, and all the other numbers obtained by changing a single digit to
produce 100, 300, 400, ··· 900, or 210, 220, 230, ··· 290 which are all even.
It is valid to change 189 into 089 by changing the 1 (one) into
a 0 (zero), which then the leading zero can be removed, and then treated as if
the "new" number is 89.
Task
show the first 35 unprimeable numbers (horizontally, on one line, preferably with a title)
show the 600th unprimeable number
(optional) show the lowest unprimeable number ending in a specific decimal digit (0, 1, 2, 3, 4, 5, 6, 7, 8, 9)
(optional) use commas in the numbers where appropriate
Show all output here, on this page.
Also see
the OEIS entry: A118118 (unprimeable)
with some useful counts to compare unprimeable number
the Wiktionary entry (reference from below): (arithmetic definition) unprimeable
from the Adam Spencer book (page 200): Adam Spencer's World of Numbers (Xoum Publishing)
| #jq | jq | def digits: tostring | explode | map([.] | implode | tonumber);
def lpad($len): tostring | ($len - length) as $l | (" " * $l)[:$l] + .;
|
http://rosettacode.org/wiki/Unicode_variable_names | Unicode variable names | Task
Describe, and give a pointer to documentation on your languages use of characters beyond those of the ASCII character set in the naming of variables.
Show how to:
Set a variable with a name including the 'Δ', (delta character), to 1
Increment it
Print its value.
Related task
Case-sensitivity of identifiers
| #PHP | PHP | <?php
$Δ = 1;
++$Δ;
echo $Δ; |
http://rosettacode.org/wiki/Unicode_variable_names | Unicode variable names | Task
Describe, and give a pointer to documentation on your languages use of characters beyond those of the ASCII character set in the naming of variables.
Show how to:
Set a variable with a name including the 'Δ', (delta character), to 1
Increment it
Print its value.
Related task
Case-sensitivity of identifiers
| #PicoLisp | PicoLisp | : (setq Δ 1)
-> 1
: Δ
-> 1
: (inc 'Δ)
-> 2
: Δ
-> 2 |
http://rosettacode.org/wiki/Unicode_variable_names | Unicode variable names | Task
Describe, and give a pointer to documentation on your languages use of characters beyond those of the ASCII character set in the naming of variables.
Show how to:
Set a variable with a name including the 'Δ', (delta character), to 1
Increment it
Print its value.
Related task
Case-sensitivity of identifiers
| #Pike | Pike |
#charset utf8
void main()
{
int Δ = 1;
Δ++;
write( Δ +"\n");
}
|
http://rosettacode.org/wiki/Unbias_a_random_generator | Unbias a random generator |
P
1
{\displaystyle P_{1}}
P
0
{\displaystyle P_{0}}
P
1
{\displaystyle P_{1}}
P
0
{\displaystyle P_{0}}
P
0
{\displaystyle P_{0}}
P
1
{\displaystyle P_{1}}
Task details
Use your language's random number generator to create a function/method/subroutine/... randN that returns a one or a zero, but with one occurring, on average, 1 out of N times, where N is an integer from the range 3 to 6 inclusive.
Create a function unbiased that uses only randN as its source of randomness to become an unbiased generator of random ones and zeroes.
For N over its range, generate and show counts of the outputs of randN and unbiased(randN).
The actual unbiasing should be done by generating two numbers at a time from randN and only returning a 1 or 0 if they are different. As long as you always return the first number or always return the second number, the probabilities discussed above should take over the biased probability of randN.
This task is an implementation of Von Neumann debiasing, first described in a 1951 paper.
| #F.C5.8Drmul.C3.A6 | Fōrmulæ | RandNGen := function(n)
local v, rand;
v := [1 .. n - 1]*0;
Add(v, 1);
rand := function()
return Random(v);
end;
return rand;
end;
UnbiasedGen := function(rand)
local unbiased;
unbiased := function()
local a, b;
while true do
a := rand();
b := rand();
if a <> b then
break;
fi;
od;
return a;
end;
return unbiased;
end;
range := [2 .. 6];
v := List(range, RandNGen);
w := List(v, UnbiasedGen);
apply := gen -> Sum([1 .. 1000000], n -> gen());
# Some tests (2 is added as a witness, since in this case RandN is already unbiased)
PrintArray(TransposedMat([range, List(v, apply), List(w, apply)]));
# [ [ 2, 499991, 499041 ],
# [ 3, 333310, 500044 ],
# [ 4, 249851, 500663 ],
# [ 5, 200532, 500448 ],
# [ 6, 166746, 499859 ] ] |
http://rosettacode.org/wiki/Unbias_a_random_generator | Unbias a random generator |
P
1
{\displaystyle P_{1}}
P
0
{\displaystyle P_{0}}
P
1
{\displaystyle P_{1}}
P
0
{\displaystyle P_{0}}
P
0
{\displaystyle P_{0}}
P
1
{\displaystyle P_{1}}
Task details
Use your language's random number generator to create a function/method/subroutine/... randN that returns a one or a zero, but with one occurring, on average, 1 out of N times, where N is an integer from the range 3 to 6 inclusive.
Create a function unbiased that uses only randN as its source of randomness to become an unbiased generator of random ones and zeroes.
For N over its range, generate and show counts of the outputs of randN and unbiased(randN).
The actual unbiasing should be done by generating two numbers at a time from randN and only returning a 1 or 0 if they are different. As long as you always return the first number or always return the second number, the probabilities discussed above should take over the biased probability of randN.
This task is an implementation of Von Neumann debiasing, first described in a 1951 paper.
| #GAP | GAP | RandNGen := function(n)
local v, rand;
v := [1 .. n - 1]*0;
Add(v, 1);
rand := function()
return Random(v);
end;
return rand;
end;
UnbiasedGen := function(rand)
local unbiased;
unbiased := function()
local a, b;
while true do
a := rand();
b := rand();
if a <> b then
break;
fi;
od;
return a;
end;
return unbiased;
end;
range := [2 .. 6];
v := List(range, RandNGen);
w := List(v, UnbiasedGen);
apply := gen -> Sum([1 .. 1000000], n -> gen());
# Some tests (2 is added as a witness, since in this case RandN is already unbiased)
PrintArray(TransposedMat([range, List(v, apply), List(w, apply)]));
# [ [ 2, 499991, 499041 ],
# [ 3, 333310, 500044 ],
# [ 4, 249851, 500663 ],
# [ 5, 200532, 500448 ],
# [ 6, 166746, 499859 ] ] |
http://rosettacode.org/wiki/Two_bullet_roulette | Two bullet roulette | The following is supposedly a question given to mathematics graduates seeking jobs on Wall Street:
A revolver handgun has a revolving cylinder with six chambers for bullets.
It is loaded with the following procedure:
1. Check the first chamber to the right of the trigger for a bullet. If a bullet
is seen, the cylinder is rotated one chamber clockwise and the next chamber
checked until an empty chamber is found.
2. A cartridge containing a bullet is placed in the empty chamber.
3. The cylinder is then rotated one chamber clockwise.
To randomize the cylinder's position, the cylinder is spun, which causes the cylinder to take
a random position from 1 to 6 chamber rotations clockwise from its starting position.
When the trigger is pulled the gun will fire if there is a bullet in position 0, which is just
counterclockwise from the loading position.
The gun is unloaded by removing all cartridges from the cylinder.
According to the legend, a suicidal Russian imperial military officer plays a game of Russian
roulette by putting two bullets in a six-chamber cylinder and pulls the trigger twice.
If the gun fires with a trigger pull, this is considered a successful suicide.
The cylinder is always spun before the first shot, but it may or may not be spun after putting
in the first bullet and may or may not be spun after taking the first shot.
Which of the following situations produces the highest probability of suicide?
A. Spinning the cylinder after loading the first bullet, and spinning again after the first shot.
B. Spinning the cylinder after loading the first bullet only.
C. Spinning the cylinder after firing the first shot only.
D. Not spinning the cylinder either after loading the first bullet or after the first shot.
E. The probability is the same for all cases.
Task
Run a repeated simulation of each of the above scenario, calculating the percentage of suicide with a randomization of the four spinning, loading and firing order scenarios.
Show the results as a percentage of deaths for each type of scenario.
The hand calculated probabilities are 5/9, 7/12, 5/9, and 1/2. A correct program should produce results close enough to those to allow a correct response to the interview question.
Reference
Youtube video on the Russian 1895 Nagant revolver [[1]]
| #JavaScript | JavaScript |
let Pistol = function(method) {
this.fired = false;
this.cylinder = new Array(6).fill(false);
this.trigger = 0;
this.rshift = function() {
this.trigger = this.trigger == 0 ? 5 : this.trigger-1;
}
this.load = function() {
while (this.cylinder[this.trigger]) this.rshift();
this.cylinder[this.trigger] = true;
this.rshift();
}
// actually we don't need this here: just for completeness
this.unload = function() { this.cylinder.fill(false); }
this.spin = function() { this.trigger = Math.floor(Math.random() * 6); }
this.fire = function() {
if (this.cylinder[this.trigger]) this.fired = true;
this.rshift();
}
this.exec = function() {
if (!method) console.error('No method provided');
else {
method = method.toUpperCase();
for (let x = 0; x < method.length; x++)
switch (method[x]) {
case 'F' : this.fire(); break;
case 'L' : this.load(); break;
case 'S' : this.spin(); break;
case 'U' : this.unload(); break;
default: console.error(`Unknown character in method: ${method[x]}`);
}
return this.fired;
}
}
}
// simulating
const ITERATIONS = 25e4;
let methods = 'lslsfsf lslsff llsfsf llsff'.split(' '),
bodyCount;
console.log(`@ ${ITERATIONS.toLocaleString('en')} iterations:`);
console.log();
for (let x = 0; x < methods.length; x++) {
bodyCount = 0;
for (let y = 1; y <= ITERATIONS; y++)
if (new Pistol(methods[x]).exec()) bodyCount++;
console.log(`${methods[x]}:`);
console.log(`deaths: ${bodyCount.toLocaleString('en')} (${(bodyCount / ITERATIONS * 100).toPrecision(3)} %) `);
console.log();
}
|
http://rosettacode.org/wiki/Unix/ls | Unix/ls | Task
Write a program that will list everything in the current folder, similar to:
the Unix utility “ls” [1] or
the Windows terminal command “DIR”
The output must be sorted, but printing extended details and producing multi-column output is not required.
Example output
For the list of paths:
/foo/bar
/foo/bar/1
/foo/bar/2
/foo/bar/a
/foo/bar/b
When the program is executed in `/foo`, it should print:
bar
and when the program is executed in `/foo/bar`, it should print:
1
2
a
b
| #OCaml | OCaml | let () =
Array.iter print_endline (
Sys.readdir Sys.argv.(1) ) |
http://rosettacode.org/wiki/Unix/ls | Unix/ls | Task
Write a program that will list everything in the current folder, similar to:
the Unix utility “ls” [1] or
the Windows terminal command “DIR”
The output must be sorted, but printing extended details and producing multi-column output is not required.
Example output
For the list of paths:
/foo/bar
/foo/bar/1
/foo/bar/2
/foo/bar/a
/foo/bar/b
When the program is executed in `/foo`, it should print:
bar
and when the program is executed in `/foo/bar`, it should print:
1
2
a
b
| #PARI.2FGP | PARI/GP | system("dir/b/on") |
http://rosettacode.org/wiki/Vector_products | Vector products | A vector is defined as having three dimensions as being represented by an ordered collection of three numbers: (X, Y, Z).
If you imagine a graph with the x and y axis being at right angles to each other and having a third, z axis coming out of the page, then a triplet of numbers, (X, Y, Z) would represent a point in the region, and a vector from the origin to the point.
Given the vectors:
A = (a1, a2, a3)
B = (b1, b2, b3)
C = (c1, c2, c3)
then the following common vector products are defined:
The dot product (a scalar quantity)
A • B = a1b1 + a2b2 + a3b3
The cross product (a vector quantity)
A x B = (a2b3 - a3b2, a3b1 - a1b3, a1b2 - a2b1)
The scalar triple product (a scalar quantity)
A • (B x C)
The vector triple product (a vector quantity)
A x (B x C)
Task
Given the three vectors:
a = ( 3, 4, 5)
b = ( 4, 3, 5)
c = (-5, -12, -13)
Create a named function/subroutine/method to compute the dot product of two vectors.
Create a function to compute the cross product of two vectors.
Optionally create a function to compute the scalar triple product of three vectors.
Optionally create a function to compute the vector triple product of three vectors.
Compute and display: a • b
Compute and display: a x b
Compute and display: a • (b x c), the scalar triple product.
Compute and display: a x (b x c), the vector triple product.
References
A starting page on Wolfram MathWorld is Vector Multiplication .
Wikipedia dot product.
Wikipedia cross product.
Wikipedia triple product.
Related tasks
Dot product
Quaternion type
| #Sidef | Sidef | class MyVector(x, y, z) {
method ∙(vec) {
[self{:x,:y,:z}] »*« [vec{:x,:y,:z}] «+»
}
method ⨉(vec) {
MyVector(self.y*vec.z - self.z*vec.y,
self.z*vec.x - self.x*vec.z,
self.x*vec.y - self.y*vec.x)
}
method to_s {
"(#{x}, #{y}, #{z})"
}
}
var a = MyVector(3, 4, 5)
var b = MyVector(4, 3, 5)
var c = MyVector(-5, -12, -13)
say "a=#{a}; b=#{b}; c=#{c};"
say "a ∙ b = #{a ∙ b}"
say "a ⨉ b = #{a ⨉ b}"
say "a ∙ (b ⨉ c) = #{a ∙ (b ⨉ c)}"
say "a ⨉ (b ⨉ c) = #{a ⨉ (b ⨉ c)}" |
http://rosettacode.org/wiki/Undefined_values | Undefined values | #PureBasic | PureBasic | If OpenConsole()
CompilerIf Defined(var, #PB_Variable)
PrintN("var is defined at first check")
CompilerElse
PrintN("var is undefined at first check")
Define var
CompilerEndIf
CompilerIf Defined(var, #PB_Variable)
PrintN("var is defined at second check")
CompilerElse
PrintN("var is undefined at second check")
Define var
CompilerEndIf
Print(#CRLF$ + #CRLF$ + "Press ENTER to exit")
Input()
CloseConsole()
EndIf |
|
http://rosettacode.org/wiki/Undefined_values | Undefined values | #Python | Python | # Check to see whether a name is defined
try: name
except NameError: print "name is undefined at first check"
# Create a name, giving it a string value
name = "Chocolate"
# Check to see whether the name is defined now.
try: name
except NameError: print "name is undefined at second check"
# Remove the definition of the name.
del name
# Check to see whether it is defined after the explicit removal.
try: name
except NameError: print "name is undefined at third check"
# Recreate the name, giving it a value of 42
name = 42
# Check to see whether the name is defined now.
try: name
except NameError: print "name is undefined at fourth check"
# Because most of the output is conditional, this serves as
# a clear indicator that the program has run to completion.
print "Done" |
|
http://rosettacode.org/wiki/Unicode_strings | Unicode strings | As the world gets smaller each day, internationalization becomes more and more important. For handling multiple languages, Unicode is your best friend.
It is a very capable tool, but also quite complex compared to older single- and double-byte character encodings.
How well prepared is your programming language for Unicode?
Task
Discuss and demonstrate its unicode awareness and capabilities.
Some suggested topics:
How easy is it to present Unicode strings in source code?
Can Unicode literals be written directly, or be part of identifiers/keywords/etc?
How well can the language communicate with the rest of the world?
Is it good at input/output with Unicode?
Is it convenient to manipulate Unicode strings in the language?
How broad/deep does the language support Unicode?
What encodings (e.g. UTF-8, UTF-16, etc) can be used?
Does it support normalization?
Note
This task is a bit unusual in that it encourages general discussion rather than clever coding.
See also
Unicode variable names
Terminal control/Display an extended character
| #Nim | Nim | use utf8; |
http://rosettacode.org/wiki/Unicode_strings | Unicode strings | As the world gets smaller each day, internationalization becomes more and more important. For handling multiple languages, Unicode is your best friend.
It is a very capable tool, but also quite complex compared to older single- and double-byte character encodings.
How well prepared is your programming language for Unicode?
Task
Discuss and demonstrate its unicode awareness and capabilities.
Some suggested topics:
How easy is it to present Unicode strings in source code?
Can Unicode literals be written directly, or be part of identifiers/keywords/etc?
How well can the language communicate with the rest of the world?
Is it good at input/output with Unicode?
Is it convenient to manipulate Unicode strings in the language?
How broad/deep does the language support Unicode?
What encodings (e.g. UTF-8, UTF-16, etc) can be used?
Does it support normalization?
Note
This task is a bit unusual in that it encourages general discussion rather than clever coding.
See also
Unicode variable names
Terminal control/Display an extended character
| #Oforth | Oforth | use utf8; |
http://rosettacode.org/wiki/Unicode_strings | Unicode strings | As the world gets smaller each day, internationalization becomes more and more important. For handling multiple languages, Unicode is your best friend.
It is a very capable tool, but also quite complex compared to older single- and double-byte character encodings.
How well prepared is your programming language for Unicode?
Task
Discuss and demonstrate its unicode awareness and capabilities.
Some suggested topics:
How easy is it to present Unicode strings in source code?
Can Unicode literals be written directly, or be part of identifiers/keywords/etc?
How well can the language communicate with the rest of the world?
Is it good at input/output with Unicode?
Is it convenient to manipulate Unicode strings in the language?
How broad/deep does the language support Unicode?
What encodings (e.g. UTF-8, UTF-16, etc) can be used?
Does it support normalization?
Note
This task is a bit unusual in that it encourages general discussion rather than clever coding.
See also
Unicode variable names
Terminal control/Display an extended character
| #Ol | Ol | use utf8; |
http://rosettacode.org/wiki/Twin_primes | Twin primes | Twin primes are pairs of natural numbers (P1 and P2) that satisfy the following:
P1 and P2 are primes
P1 + 2 = P2
Task
Write a program that displays the number of pairs of twin primes that can be found under a user-specified number
(P1 < user-specified number & P2 < user-specified number).
Extension
Find all twin prime pairs under 100000, 10000000 and 1000000000.
What is the time complexity of the program? Are there ways to reduce computation time?
Examples
> Search Size: 100
> 8 twin prime pairs.
> Search Size: 1000
> 35 twin prime pairs.
Also see
The OEIS entry: A001097: Twin primes.
The OEIS entry: A167874: The number of distinct primes < 10^n which are members of twin-prime pairs.
The OEIS entry: A077800: List of twin primes {p, p+2}, with repetition.
The OEIS entry: A007508: Number of twin prime pairs below 10^n.
| #C.23 | C# | using System;
class Program {
static uint[] res = new uint[10];
static uint ri = 1, p = 10, count = 0;
static void TabulateTwinPrimes(uint bound) {
if (bound < 5) return; count++;
uint cl = (bound - 1) >> 1, i = 1, j,
limit = (uint)(Math.Sqrt(bound) - 1) >> 1;
var comp = new bool[cl]; bool lp;
for (j = 3; j < cl; j += 3) comp[j] = true;
while (i < limit) {
if (lp = !comp[i]) {
uint pr = (i << 1) + 3;
for (j = (pr * pr - 2) >> 1; j < cl; j += pr)
comp[j] = true;
}
if (!comp[++i]) {
uint pr = (i << 1) + 3;
if (lp) {
if (pr > p) {
res[ri++] = count;
p *= 10;
}
count++;
i++;
}
for (j = (pr * pr - 2) >> 1; j < cl; j += pr)
comp[j] = true;
}
}
cl--;
while (i < cl) {
lp = !comp[i++];
if (!comp[i] && lp) {
if ((i++ << 1) + 3 > p) {
res[ri++] = count;
p *= 10;
}
count++;
}
}
res[ri] = count;
}
static void Main(string[] args) {
var sw = System.Diagnostics.Stopwatch.StartNew();
string fmt = "{0,9:n0} twin primes below {1,-13:n0}";
TabulateTwinPrimes(1_000_000_000);
sw.Stop();
p = 1;
for (var j = 1; j <= ri; j++)
Console.WriteLine(fmt, res[j], p *= 10);
Console.Write("{0} sec", sw.Elapsed.TotalSeconds);
}
} |
http://rosettacode.org/wiki/Unprimeable_numbers | Unprimeable numbers | Definitions
As used here, all unprimeable numbers (positive integers) are always expressed in base ten.
───── Definition from OEIS ─────:
Unprimeable numbers are composite numbers that always remain composite when a single decimal digit of the number is changed.
───── Definition from Wiktionary (referenced from Adam Spencer's book) ─────:
(arithmetic) that cannot be turned into a prime number by changing just one of its digits to any other
digit. (sic)
Unprimeable numbers are also spelled: unprimable.
All one─ and two─digit numbers can be turned into primes by changing a single decimal digit.
Examples
190 isn't unprimeable, because by changing the zero digit into a three yields 193, which is a prime.
The number 200 is unprimeable, since none of the numbers 201, 202, 203, ··· 209 are
prime, and all the other numbers obtained by changing a single digit to
produce 100, 300, 400, ··· 900, or 210, 220, 230, ··· 290 which are all even.
It is valid to change 189 into 089 by changing the 1 (one) into
a 0 (zero), which then the leading zero can be removed, and then treated as if
the "new" number is 89.
Task
show the first 35 unprimeable numbers (horizontally, on one line, preferably with a title)
show the 600th unprimeable number
(optional) show the lowest unprimeable number ending in a specific decimal digit (0, 1, 2, 3, 4, 5, 6, 7, 8, 9)
(optional) use commas in the numbers where appropriate
Show all output here, on this page.
Also see
the OEIS entry: A118118 (unprimeable)
with some useful counts to compare unprimeable number
the Wiktionary entry (reference from below): (arithmetic definition) unprimeable
from the Adam Spencer book (page 200): Adam Spencer's World of Numbers (Xoum Publishing)
| #Julia | Julia | using Primes, Lazy, Formatting
function isunprimeable(n)
dvec = digits(n)
for pos in 1:length(dvec), newdigit in 0:9
olddigit, dvec[pos] = dvec[pos], newdigit
isprime(foldr((i, j) -> i + 10j, dvec)) && return false
dvec[pos] = olddigit
end
return true
end
println("First 35 unprimeables: ", take(35, filter(isunprimeable, Lazy.range())))
println("\nThe 600th unprimeable is ",
collect(take(600, filter(isunprimeable, Lazy.range())))[end])
println("\nDigit First unprimeable ending with that digit")
println("-----------------------------------------")
for dig in 0:9
n = first(filter(x -> (x % 10 == dig) && isunprimeable(x), Lazy.range()))
println(" $dig ", lpad(format(n, commas=true), 9))
end
|
http://rosettacode.org/wiki/Unicode_variable_names | Unicode variable names | Task
Describe, and give a pointer to documentation on your languages use of characters beyond those of the ASCII character set in the naming of variables.
Show how to:
Set a variable with a name including the 'Δ', (delta character), to 1
Increment it
Print its value.
Related task
Case-sensitivity of identifiers
| #PowerShell | PowerShell |
$Δ = 2
$π = 3.14
$π*$Δ
|
http://rosettacode.org/wiki/Unicode_variable_names | Unicode variable names | Task
Describe, and give a pointer to documentation on your languages use of characters beyond those of the ASCII character set in the naming of variables.
Show how to:
Set a variable with a name including the 'Δ', (delta character), to 1
Increment it
Print its value.
Related task
Case-sensitivity of identifiers
| #Prolog | Prolog | % Unicode in predicate names:
是. % be: means, approximately, "True".
不是 :- \+ 是. % not be: means, approximately, "False". Defined as not 是.
% Unicode in variable names:
test(Garçon, Δ) :-
Garçon = boy,
Δ = delta.
% Call test2(1, Result) to have 2 assigned to Result.
test2(Δ, R) :- R is Δ + 1. |
http://rosettacode.org/wiki/Unicode_variable_names | Unicode variable names | Task
Describe, and give a pointer to documentation on your languages use of characters beyond those of the ASCII character set in the naming of variables.
Show how to:
Set a variable with a name including the 'Δ', (delta character), to 1
Increment it
Print its value.
Related task
Case-sensitivity of identifiers
| #Python | Python | >>> Δx = 1
>>> Δx += 1
>>> print(Δx)
2
>>> |
http://rosettacode.org/wiki/Unicode_variable_names | Unicode variable names | Task
Describe, and give a pointer to documentation on your languages use of characters beyond those of the ASCII character set in the naming of variables.
Show how to:
Set a variable with a name including the 'Δ', (delta character), to 1
Increment it
Print its value.
Related task
Case-sensitivity of identifiers
| #R | R | f <- function(`∆`=1) `∆`+1
f(1) |
http://rosettacode.org/wiki/Unbias_a_random_generator | Unbias a random generator |
P
1
{\displaystyle P_{1}}
P
0
{\displaystyle P_{0}}
P
1
{\displaystyle P_{1}}
P
0
{\displaystyle P_{0}}
P
0
{\displaystyle P_{0}}
P
1
{\displaystyle P_{1}}
Task details
Use your language's random number generator to create a function/method/subroutine/... randN that returns a one or a zero, but with one occurring, on average, 1 out of N times, where N is an integer from the range 3 to 6 inclusive.
Create a function unbiased that uses only randN as its source of randomness to become an unbiased generator of random ones and zeroes.
For N over its range, generate and show counts of the outputs of randN and unbiased(randN).
The actual unbiasing should be done by generating two numbers at a time from randN and only returning a 1 or 0 if they are different. As long as you always return the first number or always return the second number, the probabilities discussed above should take over the biased probability of randN.
This task is an implementation of Von Neumann debiasing, first described in a 1951 paper.
| #Go | Go | package main
import (
"fmt"
"math/rand"
)
const samples = 1e6
func main() {
fmt.Println("Generator 1 count 0 count % 1 count")
for n := 3; n <= 6; n++ {
// function randN, per task description
randN := func() int {
if rand.Intn(n) == 0 {
return 1
}
return 0
}
var b [2]int
for x := 0; x < samples; x++ {
b[randN()]++
}
fmt.Printf("randN(%d) %7d %7d %5.2f%%\n",
n, b[1], b[0], float64(b[1])*100/samples)
// function unbiased, per task description
unbiased := func() (b int) {
for b = randN(); b == randN(); b = randN() {
}
return
}
var u [2]int
for x := 0; x < samples; x++ {
u[unbiased()]++
}
fmt.Printf("unbiased %7d %7d %5.2f%%\n",
u[1], u[0], float64(u[1])*100/samples)
}
} |
http://rosettacode.org/wiki/Truncate_a_file | Truncate a file | Task
Truncate a file to a specific length. This should be implemented as a routine that takes two parameters: the filename and the required file length (in bytes).
Truncation can be achieved using system or library calls intended for such a task, if such methods exist, or by creating a temporary file of a reduced size and renaming it, after first deleting the original file, if no other method is available. The file may contain non human readable binary data in an unspecified format, so the routine should be "binary safe", leaving the contents of the untruncated part of the file unchanged.
If the specified filename does not exist, or the provided length is not less than the current file length, then the routine should raise an appropriate error condition.
On some systems, the provided file truncation facilities might not change the file or may extend the file, if the specified length is greater than the current length of the file.
This task permits the use of such facilities. However, such behaviour should be noted, or optionally a warning message relating to an non change or increase in file size may be implemented.
| #11l | 11l | F truncate_file(name, length)
I !fs:is_file(name)
R 0B
I length >= fs:file_size(name)
R 0B
fs:resize_file(name, length)
R 1B |
http://rosettacode.org/wiki/Two_bullet_roulette | Two bullet roulette | The following is supposedly a question given to mathematics graduates seeking jobs on Wall Street:
A revolver handgun has a revolving cylinder with six chambers for bullets.
It is loaded with the following procedure:
1. Check the first chamber to the right of the trigger for a bullet. If a bullet
is seen, the cylinder is rotated one chamber clockwise and the next chamber
checked until an empty chamber is found.
2. A cartridge containing a bullet is placed in the empty chamber.
3. The cylinder is then rotated one chamber clockwise.
To randomize the cylinder's position, the cylinder is spun, which causes the cylinder to take
a random position from 1 to 6 chamber rotations clockwise from its starting position.
When the trigger is pulled the gun will fire if there is a bullet in position 0, which is just
counterclockwise from the loading position.
The gun is unloaded by removing all cartridges from the cylinder.
According to the legend, a suicidal Russian imperial military officer plays a game of Russian
roulette by putting two bullets in a six-chamber cylinder and pulls the trigger twice.
If the gun fires with a trigger pull, this is considered a successful suicide.
The cylinder is always spun before the first shot, but it may or may not be spun after putting
in the first bullet and may or may not be spun after taking the first shot.
Which of the following situations produces the highest probability of suicide?
A. Spinning the cylinder after loading the first bullet, and spinning again after the first shot.
B. Spinning the cylinder after loading the first bullet only.
C. Spinning the cylinder after firing the first shot only.
D. Not spinning the cylinder either after loading the first bullet or after the first shot.
E. The probability is the same for all cases.
Task
Run a repeated simulation of each of the above scenario, calculating the percentage of suicide with a randomization of the four spinning, loading and firing order scenarios.
Show the results as a percentage of deaths for each type of scenario.
The hand calculated probabilities are 5/9, 7/12, 5/9, and 1/2. A correct program should produce results close enough to those to allow a correct response to the interview question.
Reference
Youtube video on the Russian 1895 Nagant revolver [[1]]
| #Julia | Julia | const cyl = zeros(Bool, 6)
function load()
while cyl[1]
cyl .= circshift(cyl, 1)
end
cyl[1] = true
cyl .= circshift(cyl, 1)
end
spin() = (cyl .= circshift(cyl, rand(1:6)))
fire() = (shot = cyl[1]; cyl .= circshift(cyl, 1); shot)
function LSLSFSF()
cyl .= 0
load(); spin(); load(); spin()
fire() && return true
spin(); return fire()
end
function LSLSFF()
cyl .= 0
load(); spin(); load(); spin()
fire() && return true
return fire()
end
function LLSFSF()
cyl .= 0
load(); load(); spin()
fire() && return true
spin(); return fire()
end
function LLSFF()
cyl .= 0
load(); load(); spin()
fire() && return true
return fire()
end
function testmethods(N = 10000000)
for (name, method) in [("load, spin, load, spin, fire, spin, fire", LSLSFSF),
("load, spin, load, spin, fire, fire", LSLSFF),
("load, load, spin, fire, spin, fire", LLSFSF),
("load, load, spin, fire, fire", LLSFF)]
percentage = 100 * sum([method() for _ in 1:N]) / N
println("Method $name produces $percentage per cent deaths.")
end
end
testmethods()
|
http://rosettacode.org/wiki/Two_bullet_roulette | Two bullet roulette | The following is supposedly a question given to mathematics graduates seeking jobs on Wall Street:
A revolver handgun has a revolving cylinder with six chambers for bullets.
It is loaded with the following procedure:
1. Check the first chamber to the right of the trigger for a bullet. If a bullet
is seen, the cylinder is rotated one chamber clockwise and the next chamber
checked until an empty chamber is found.
2. A cartridge containing a bullet is placed in the empty chamber.
3. The cylinder is then rotated one chamber clockwise.
To randomize the cylinder's position, the cylinder is spun, which causes the cylinder to take
a random position from 1 to 6 chamber rotations clockwise from its starting position.
When the trigger is pulled the gun will fire if there is a bullet in position 0, which is just
counterclockwise from the loading position.
The gun is unloaded by removing all cartridges from the cylinder.
According to the legend, a suicidal Russian imperial military officer plays a game of Russian
roulette by putting two bullets in a six-chamber cylinder and pulls the trigger twice.
If the gun fires with a trigger pull, this is considered a successful suicide.
The cylinder is always spun before the first shot, but it may or may not be spun after putting
in the first bullet and may or may not be spun after taking the first shot.
Which of the following situations produces the highest probability of suicide?
A. Spinning the cylinder after loading the first bullet, and spinning again after the first shot.
B. Spinning the cylinder after loading the first bullet only.
C. Spinning the cylinder after firing the first shot only.
D. Not spinning the cylinder either after loading the first bullet or after the first shot.
E. The probability is the same for all cases.
Task
Run a repeated simulation of each of the above scenario, calculating the percentage of suicide with a randomization of the four spinning, loading and firing order scenarios.
Show the results as a percentage of deaths for each type of scenario.
The hand calculated probabilities are 5/9, 7/12, 5/9, and 1/2. A correct program should produce results close enough to those to allow a correct response to the interview question.
Reference
Youtube video on the Russian 1895 Nagant revolver [[1]]
| #Kotlin | Kotlin | import kotlin.random.Random
val cylinder = Array(6) { false }
fun rShift() {
val t = cylinder[cylinder.size - 1]
for (i in (0 until cylinder.size - 1).reversed()) {
cylinder[i + 1] = cylinder[i]
}
cylinder[0] = t
}
fun unload() {
for (i in cylinder.indices) {
cylinder[i] = false
}
}
fun load() {
while (cylinder[0]) {
rShift()
}
cylinder[0] = true
rShift()
}
fun spin() {
val lim = Random.nextInt(0, 6) + 1
for (i in 1..lim) {
rShift()
}
}
fun fire(): Boolean {
val shot = cylinder[0]
rShift()
return shot
}
fun method(s: String): Int {
unload()
for (c in s) {
when (c) {
'L' -> {
load()
}
'S' -> {
spin()
}
'F' -> {
if (fire()) {
return 1
}
}
}
}
return 0
}
fun mString(s: String): String {
val buf = StringBuilder()
fun append(txt: String) {
if (buf.isNotEmpty()) {
buf.append(", ")
}
buf.append(txt)
}
for (c in s) {
when (c) {
'L' -> {
append("load")
}
'S' -> {
append("spin")
}
'F' -> {
append("fire")
}
}
}
return buf.toString()
}
fun test(src: String) {
val tests = 100000
var sum = 0
for (t in 0..tests) {
sum += method(src)
}
val str = mString(src)
val pc = 100.0 * sum / tests
println("%-40s produces %6.3f%% deaths.".format(str, pc))
}
fun main() {
test("LSLSFSF");
test("LSLSFF");
test("LLSFSF");
test("LLSFF");
} |
http://rosettacode.org/wiki/Unix/ls | Unix/ls | Task
Write a program that will list everything in the current folder, similar to:
the Unix utility “ls” [1] or
the Windows terminal command “DIR”
The output must be sorted, but printing extended details and producing multi-column output is not required.
Example output
For the list of paths:
/foo/bar
/foo/bar/1
/foo/bar/2
/foo/bar/a
/foo/bar/b
When the program is executed in `/foo`, it should print:
bar
and when the program is executed in `/foo/bar`, it should print:
1
2
a
b
| #Pascal | Pascal |
Program ls; {To list the names of all files/directories in the current directory.}
Uses DOS;
var DirInfo: SearchRec; {Predefined. See page 403 of the Turbo Pascal 4 manual.}
BEGIN
FindFirst('*.*',AnyFile,DirInfo); {AnyFile means any file name OR directory name.}
While DOSerror = 0 do {Result of FindFirst/Next not being a function, damnit.}
begin
WriteLn(DirInfo.Name);
FindNext(DirInfo);
end;
END.
|
http://rosettacode.org/wiki/Unix/ls | Unix/ls | Task
Write a program that will list everything in the current folder, similar to:
the Unix utility “ls” [1] or
the Windows terminal command “DIR”
The output must be sorted, but printing extended details and producing multi-column output is not required.
Example output
For the list of paths:
/foo/bar
/foo/bar/1
/foo/bar/2
/foo/bar/a
/foo/bar/b
When the program is executed in `/foo`, it should print:
bar
and when the program is executed in `/foo/bar`, it should print:
1
2
a
b
| #Perl | Perl | opendir my $handle, '.' or die "Couldnt open current directory: $!";
while (readdir $handle) {
print "$_\n";
}
closedir $handle; |
http://rosettacode.org/wiki/Vector_products | Vector products | A vector is defined as having three dimensions as being represented by an ordered collection of three numbers: (X, Y, Z).
If you imagine a graph with the x and y axis being at right angles to each other and having a third, z axis coming out of the page, then a triplet of numbers, (X, Y, Z) would represent a point in the region, and a vector from the origin to the point.
Given the vectors:
A = (a1, a2, a3)
B = (b1, b2, b3)
C = (c1, c2, c3)
then the following common vector products are defined:
The dot product (a scalar quantity)
A • B = a1b1 + a2b2 + a3b3
The cross product (a vector quantity)
A x B = (a2b3 - a3b2, a3b1 - a1b3, a1b2 - a2b1)
The scalar triple product (a scalar quantity)
A • (B x C)
The vector triple product (a vector quantity)
A x (B x C)
Task
Given the three vectors:
a = ( 3, 4, 5)
b = ( 4, 3, 5)
c = (-5, -12, -13)
Create a named function/subroutine/method to compute the dot product of two vectors.
Create a function to compute the cross product of two vectors.
Optionally create a function to compute the scalar triple product of three vectors.
Optionally create a function to compute the vector triple product of three vectors.
Compute and display: a • b
Compute and display: a x b
Compute and display: a • (b x c), the scalar triple product.
Compute and display: a x (b x c), the vector triple product.
References
A starting page on Wolfram MathWorld is Vector Multiplication .
Wikipedia dot product.
Wikipedia cross product.
Wikipedia triple product.
Related tasks
Dot product
Quaternion type
| #Simula | Simula | BEGIN
CLASS VECTOR(I,J,K); REAL I,J,K;;
REAL PROCEDURE DOTPRODUCT(A,B); REF(VECTOR) A,B;
DOTPRODUCT := A.I*B.I+A.J*B.J+A.K*B.K;
REF(VECTOR) PROCEDURE CROSSPRODUCT(A,B); REF(VECTOR) A,B;
CROSSPRODUCT :- NEW VECTOR(A.J*B.K - A.K*B.J,
A.K*B.I - A.I*B.K,
A.I*B.J - A.J*B.I);
REAL PROCEDURE SCALARTRIPLEPRODUCT(A,B,C); REF(VECTOR) A,B,C;
SCALARTRIPLEPRODUCT := DOTPRODUCT(A,CROSSPRODUCT(B,C));
REF(VECTOR) PROCEDURE VECTORTRIPLEPRODUCT(A,B,C); REF(VECTOR) A,B,C;
VECTORTRIPLEPRODUCT :- CROSSPRODUCT(A,CROSSPRODUCT(B,C));
PROCEDURE OUTR(X); REAL X;
OUTFIX(X,6,0);
PROCEDURE OUTVECTOR(A); REF(VECTOR) A;
BEGIN
OUTTEXT("("); OUTR(A.I);
OUTTEXT(", "); OUTR(A.J);
OUTTEXT(", "); OUTR(A.K); OUTTEXT(")");
END;
BEGIN
REF(VECTOR) A,B,C;
A :- NEW VECTOR(3, 4, 5);
B :- NEW VECTOR(4, 3, 5);
C :- NEW VECTOR(-5, -12, -13);
OUTTEXT("A = "); OUTVECTOR(A);
OUTIMAGE;
OUTTEXT("B = "); OUTVECTOR(B);
OUTIMAGE;
OUTTEXT("C = "); OUTVECTOR(C);
OUTIMAGE;
OUTTEXT("A . B = "); OUTR(DOTPRODUCT(A,B));
OUTIMAGE;
OUTTEXT("A X B = "); OUTVECTOR(CROSSPRODUCT(A,B));
OUTIMAGE;
OUTTEXT("A . (B X C) = "); OUTR(SCALARTRIPLEPRODUCT(A,B,C));
OUTIMAGE;
OUTTEXT("A X (B X C) = "); OUTVECTOR(VECTORTRIPLEPRODUCT(A,B,C));
OUTIMAGE;
END;
END; |
http://rosettacode.org/wiki/Undefined_values | Undefined values | #R | R |
exists("x")
|
|
http://rosettacode.org/wiki/Undefined_values | Undefined values | #Racket | Racket |
-> (letrec ([x x]) x)
#<undefined>
|
|
http://rosettacode.org/wiki/Unicode_strings | Unicode strings | As the world gets smaller each day, internationalization becomes more and more important. For handling multiple languages, Unicode is your best friend.
It is a very capable tool, but also quite complex compared to older single- and double-byte character encodings.
How well prepared is your programming language for Unicode?
Task
Discuss and demonstrate its unicode awareness and capabilities.
Some suggested topics:
How easy is it to present Unicode strings in source code?
Can Unicode literals be written directly, or be part of identifiers/keywords/etc?
How well can the language communicate with the rest of the world?
Is it good at input/output with Unicode?
Is it convenient to manipulate Unicode strings in the language?
How broad/deep does the language support Unicode?
What encodings (e.g. UTF-8, UTF-16, etc) can be used?
Does it support normalization?
Note
This task is a bit unusual in that it encourages general discussion rather than clever coding.
See also
Unicode variable names
Terminal control/Display an extended character
| #Perl | Perl | use utf8; |
http://rosettacode.org/wiki/Unicode_strings | Unicode strings | As the world gets smaller each day, internationalization becomes more and more important. For handling multiple languages, Unicode is your best friend.
It is a very capable tool, but also quite complex compared to older single- and double-byte character encodings.
How well prepared is your programming language for Unicode?
Task
Discuss and demonstrate its unicode awareness and capabilities.
Some suggested topics:
How easy is it to present Unicode strings in source code?
Can Unicode literals be written directly, or be part of identifiers/keywords/etc?
How well can the language communicate with the rest of the world?
Is it good at input/output with Unicode?
Is it convenient to manipulate Unicode strings in the language?
How broad/deep does the language support Unicode?
What encodings (e.g. UTF-8, UTF-16, etc) can be used?
Does it support normalization?
Note
This task is a bit unusual in that it encourages general discussion rather than clever coding.
See also
Unicode variable names
Terminal control/Display an extended character
| #Phix | Phix | (in '(iconv "-f" "ISO-8859-15" "file.txt") (line)) |
http://rosettacode.org/wiki/Unicode_strings | Unicode strings | As the world gets smaller each day, internationalization becomes more and more important. For handling multiple languages, Unicode is your best friend.
It is a very capable tool, but also quite complex compared to older single- and double-byte character encodings.
How well prepared is your programming language for Unicode?
Task
Discuss and demonstrate its unicode awareness and capabilities.
Some suggested topics:
How easy is it to present Unicode strings in source code?
Can Unicode literals be written directly, or be part of identifiers/keywords/etc?
How well can the language communicate with the rest of the world?
Is it good at input/output with Unicode?
Is it convenient to manipulate Unicode strings in the language?
How broad/deep does the language support Unicode?
What encodings (e.g. UTF-8, UTF-16, etc) can be used?
Does it support normalization?
Note
This task is a bit unusual in that it encourages general discussion rather than clever coding.
See also
Unicode variable names
Terminal control/Display an extended character
| #PicoLisp | PicoLisp | (in '(iconv "-f" "ISO-8859-15" "file.txt") (line)) |
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