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http://rosettacode.org/wiki/Determinant_and_permanent
Determinant and permanent
For a given matrix, return the determinant and the permanent of the matrix. The determinant is given by det ( A ) = ∑ σ sgn ⁡ ( σ ) ∏ i = 1 n M i , σ i {\displaystyle \det(A)=\sum _{\sigma }\operatorname {sgn}(\sigma )\prod _{i=1}^{n}M_{i,\sigma _{i}}} while the permanent is given by ...
#FreeBASIC
FreeBASIC
sub make_S( M() as double, S() as double, i as uinteger, j as uinteger ) 'removes row j, column i from the matrix, stores result in S() dim as uinteger ii, jj, size=ubound(M), ix, jx for ii = 1 to size-1 if ii<i then ix = ii else ix = ii + 1 for jj = 1 to size-1 if jj<j then jx =...
http://rosettacode.org/wiki/Detect_division_by_zero
Detect division by zero
Task Write a function to detect a   divide by zero error   without checking if the denominator is zero.
#CLU
CLU
% This will catch a divide-by-zero exception and % return a oneof instead, with either the result or div_by_zero. % Overflow and underflow are resignaled. check_div = proc [T: type] (a, b: T) returns (otype) signals (overflow, underflow) where T has div: proctype (T,T) returns (T) ...
http://rosettacode.org/wiki/Detect_division_by_zero
Detect division by zero
Task Write a function to detect a   divide by zero error   without checking if the denominator is zero.
#COBOL
COBOL
DIVIDE foo BY bar GIVING foobar ON SIZE ERROR DISPLAY "Division by zero detected!" END-DIVIDE
http://rosettacode.org/wiki/Determine_if_a_string_is_numeric
Determine if a string is numeric
Task Create a boolean function which takes in a string and tells whether it is a numeric string (floating point and negative numbers included) in the syntax the language uses for numeric literals or numbers converted from strings. Other tasks related to string operations: Metrics Array length String length Cop...
#Befunge
Befunge
~:0\`#v_:"+"-!#v_:"-"-!#v_::"E"-\"e"-*#v_ v v _v# < < 0< >~:0\`#v_>::"0"-0\`\"9"-0`+!#v_:"."-!#v_::"E"-\"e"-*!#v_ v ^ $< > > $ v >~:0\`#v_>::"0"-0\`\"9"-0`+!#v_:"."-!#v_::"E"-\"e"-*...
http://rosettacode.org/wiki/Determine_if_a_string_is_numeric
Determine if a string is numeric
Task Create a boolean function which takes in a string and tells whether it is a numeric string (floating point and negative numbers included) in the syntax the language uses for numeric literals or numbers converted from strings. Other tasks related to string operations: Metrics Array length String length Cop...
#Bracmat
Bracmat
43257349578692:/ F   260780243875083/35587980:/ S   247/30:~/# F   80000000000:~/# S
http://rosettacode.org/wiki/Determine_if_a_string_has_all_unique_characters
Determine if a string has all unique characters
Task Given a character string   (which may be empty, or have a length of zero characters):   create a function/procedure/routine to:   determine if all the characters in the string are unique   indicate if or which character is duplicated and where   display each string and its length   (as the strings are being ...
#D
D
import std.stdio;   void uniqueCharacters(string str) { writefln("input: `%s`, length: %d", str, str.length); foreach (i; 0 .. str.length) { foreach (j; i + 1 .. str.length) { if (str[i] == str[j]) { writeln("String contains a repeated character."); writefln("...
http://rosettacode.org/wiki/Determine_if_a_string_is_collapsible
Determine if a string is collapsible
Determine if a character string is   collapsible. And if so,   collapse the string   (by removing   immediately repeated   characters). If a character string has   immediately repeated   character(s),   the repeated characters are to be deleted (removed),   but not the primary (1st) character(s). An   immediatel...
#Haskell
Haskell
import Text.Printf (printf) import Data.Maybe (catMaybes) import Control.Monad (guard)   input :: [String] input = [ "" , "The better the 4-wheel drive, the further you'll be from help when ya get stuck!" , "headmistressship" , "\"If I were two-faced, would I be wearing this one?\" --- Abraham L...
http://rosettacode.org/wiki/Determine_if_a_string_is_collapsible
Determine if a string is collapsible
Determine if a character string is   collapsible. And if so,   collapse the string   (by removing   immediately repeated   characters). If a character string has   immediately repeated   character(s),   the repeated characters are to be deleted (removed),   but not the primary (1st) character(s). An   immediatel...
#J
J
STRINGS =: <;._2]0 :0 "If I were two-faced, would I be wearing this one?" --- Abraham Lincoln ..1111111111111111111111111111111111111111111111111111111111111117777888 I never give 'em hell, I just tell the truth, and they think it's hell. --- Harry S Truman ) ...
http://rosettacode.org/wiki/Determine_if_a_string_has_all_the_same_characters
Determine if a string has all the same characters
Task Given a character string   (which may be empty, or have a length of zero characters):   create a function/procedure/routine to:   determine if all the characters in the string are the same   indicate if or which character is different from the previous character   display each string and its length   (as the...
#Fortran
Fortran
  program demo_verify implicit none call homogeneous('') call homogeneous('2') call homogeneous('333') call homogeneous('.55') call homogeneous('tttTTT') call homogeneous('4444 444k') contains   subroutine homogeneous(str) character(len=*),intent(in)  :: str character(len=:),allocatable :: ch c...
http://rosettacode.org/wiki/Dining_philosophers
Dining philosophers
The dining philosophers problem illustrates non-composability of low-level synchronization primitives like semaphores. It is a modification of a problem posed by Edsger Dijkstra. Five philosophers, Aristotle, Kant, Spinoza, Marx, and Russell (the tasks) spend their time thinking and eating spaghetti. They eat at a rou...
#Mathematica_.2F_Wolfram_Language
Mathematica / Wolfram Language
names = <|1 -> "Aristotle", 2 -> "Kant", 3 -> "Spinoza", 4 -> "Marx", 5 -> "Russell"|>; n = Length[names]; rp := Pause[RandomReal[4]]; PrintTemporary[Dynamic[Array[forks, n]]]; Clear[forks]; forks[_] := Null; With[{nf = n}, ParallelDo[ With[{i1 = i, i2 = Mod[i + 1, nf, 1]}, Do[Print[names[i], " thinking"]; rp;...
http://rosettacode.org/wiki/Discordian_date
Discordian date
Task Convert a given date from the   Gregorian calendar   to the   Discordian calendar.
#MAD
MAD
R DISCORDIAN DATE CALCULATION R R PUNCH CARD SHOULD CONTAIN - R MM/DD/YYYY R IN GREGORIAN CALENDAR   NORMAL MODE IS INTEGER   VECTOR VALUES MLENGT = 0 0,0,31,59,90,120,151,181,212,243,273,304,334 VECTOR VALUES TI...
http://rosettacode.org/wiki/Dijkstra%27s_algorithm
Dijkstra's algorithm
This task has been clarified. Its programming examples are in need of review to ensure that they still fit the requirements of the task. Dijkstra's algorithm, conceived by Dutch computer scientist Edsger Dijkstra in 1956 and published in 1959, is a graph search algorithm that solves the single-source shortest path pro...
#Maxima
Maxima
load(graphs)$ g: create_graph([[1, "a"], [2, "b"], [3, "c"], [4, "d"], [5, "e"], [6, "f"]], [[[1, 2], 7], [[1, 3], 9], [[1, 6], 14], [[2, 3], 10], [[2, 4], 15], [[3, 4], 11], [[3, 6], 2], [[4, 5], 6], [[5, 6], 9]], directed)$   shortest_weighted_path(1, 5, g); /* [26, [1, 3, 4, 5]] */
http://rosettacode.org/wiki/Digital_root
Digital root
The digital root, X {\displaystyle X} , of a number, n {\displaystyle n} , is calculated: find X {\displaystyle X} as the sum of the digits of n {\displaystyle n} find a new X {\displaystyle X} by summing the digits of X {\displaystyle X} , repeating until X {\displ...
#Groovy
Groovy
class DigitalRoot { static int[] calcDigitalRoot(String number, int base) { BigInteger bi = new BigInteger(number, base) int additivePersistence = 0 if (bi.signum() < 0) { bi = bi.negate() } BigInteger biBase = BigInteger.valueOf(base) while (bi >= biBase)...
http://rosettacode.org/wiki/Digital_root/Multiplicative_digital_root
Digital root/Multiplicative digital root
The multiplicative digital root (MDR) and multiplicative persistence (MP) of a number, n {\displaystyle n} , is calculated rather like the Digital root except digits are multiplied instead of being added: Set m {\displaystyle m} to n {\displaystyle n} and i {\displaystyle i} to 0 ...
#Ring
Ring
  # Project : Digital root/Multiplicative digital root   load "stdlib.ring" root = newlist(10, 5) for r = 1 to 10 for x = 1 to 5 root[r][x] = 0 next next root2 = list(10) for y = 1 to 10 root2[y] = 0 next see "Number MDR MP" + nl num = [123321, 7739, 893, 899998] digroot(num) see nl num = 0:...
http://rosettacode.org/wiki/Digital_root/Multiplicative_digital_root
Digital root/Multiplicative digital root
The multiplicative digital root (MDR) and multiplicative persistence (MP) of a number, n {\displaystyle n} , is calculated rather like the Digital root except digits are multiplied instead of being added: Set m {\displaystyle m} to n {\displaystyle n} and i {\displaystyle i} to 0 ...
#Ruby
Ruby
def mdroot(n) mdr, persist = n, 0 until mdr < 10 do mdr = mdr.digits.inject(:*) persist += 1 end [mdr, persist] end   puts "Number: MDR MP", "====== === ==" [123321, 7739, 893, 899998].each{|n| puts "%6d:  %d  %2d" % [n, *mdroot(n)]}   counter = Hash.new{|h,k| h[k]=[]} 0.step do |i| counter[mdroot...
http://rosettacode.org/wiki/Dinesman%27s_multiple-dwelling_problem
Dinesman's multiple-dwelling problem
Task Solve Dinesman's multiple dwelling problem but in a way that most naturally follows the problem statement given below. Solutions are allowed (but not required) to parse and interpret the problem text, but should remain flexible and should state what changes to the problem text are allowed. Flexibility and ease of...
#Nim
Nim
import algorithm   type   Person {.pure.} = enum Baker, Cooper, Fletcher, Miller, Smith Floor = range[1..5]   var floors: array[Person, Floor] = [Floor 1, 2, 3, 4, 5]   while true: if floors[Baker] != 5 and floors[Cooper] != 1 and floors[Fletcher] notin [1, 5] and floors[Miller] > floors[Cooper] an...
http://rosettacode.org/wiki/Dot_product
Dot product
Task Create a function/use an in-built function, to compute the   dot product,   also known as the   scalar product   of two vectors. If possible, make the vectors of arbitrary length. As an example, compute the dot product of the vectors:   [1,  3, -5]     and   [4, -2, -1] If implementing the dot ...
#Groovy
Groovy
def dotProduct = { x, y -> assert x && y && x.size() == y.size() [x, y].transpose().collect{ xx, yy -> xx * yy }.sum() }
http://rosettacode.org/wiki/Determine_if_a_string_is_squeezable
Determine if a string is squeezable
Determine if a character string is   squeezable. And if so,   squeeze the string   (by removing any number of a   specified   immediately repeated   character). This task is very similar to the task     Determine if a character string is collapsible     except that only a specified character is   squeezed   instead...
#J
J
  dlb }.~ (=&' ' (i.) 0:) dtb #~ ([: +./\. ' '&~:) deb #~ ((+.) (1: |. (> </\)))@(' '&~:)  
http://rosettacode.org/wiki/Determine_if_a_string_is_squeezable
Determine if a string is squeezable
Determine if a character string is   squeezable. And if so,   squeeze the string   (by removing any number of a   specified   immediately repeated   character). This task is very similar to the task     Determine if a character string is collapsible     except that only a specified character is   squeezed   instead...
#Java
Java
    // Title: Determine if a string is squeezable   public class StringSqueezable {   public static void main(String[] args) { String[] testStrings = new String[] { "", "\"If I were two-faced, would I be wearing this one?\" --- Abraham Lincoln ", "..111111...
http://rosettacode.org/wiki/Deming%27s_Funnel
Deming's Funnel
W Edwards Deming was an American statistician and management guru who used physical demonstrations to illuminate his teachings. In one demonstration Deming repeatedly dropped marbles through a funnel at a target, marking where they landed, and observing the resulting pattern. He applied a sequence of "rules" to try to ...
#Java
Java
import static java.lang.Math.*; import java.util.Arrays; import java.util.function.BiFunction;   public class DemingsFunnel {   public static void main(String[] args) { double[] dxs = { -0.533, 0.270, 0.859, -0.043, -0.205, -0.127, -0.071, 0.275, 1.251, -0.231, -0.401, 0.269, 0.491, ...
http://rosettacode.org/wiki/Department_numbers
Department numbers
There is a highly organized city that has decided to assign a number to each of their departments:   police department   sanitation department   fire department Each department can have a number between   1   and   7   (inclusive). The three department numbers are to be unique (different from each other) and mu...
#ALGOL_68
ALGOL 68
BEGIN # show possible department number allocations for police, sanitation and fire departments # # the police department number must be even, all department numbers in the range 1 .. 7 # # the sum of the department numbers must be 12 # INT max department num...
http://rosettacode.org/wiki/Delegates
Delegates
A delegate is a helper object used by another object. The delegator may send the delegate certain messages, and provide a default implementation when there is no delegate or the delegate does not respond to a message. This pattern is heavily used in Cocoa framework on Mac OS X. See also wp:Delegation pattern. Objects ...
#C.2B.2B
C++
  #include <tr1/memory> #include <string> #include <iostream> #include <tr1/functional>   using namespace std; using namespace std::tr1; using std::tr1::function;   // interface for all delegates class IDelegate { public: virtual ~IDelegate() {} };   //interface for delegates supporting thing class IThing { public...
http://rosettacode.org/wiki/Determine_if_two_triangles_overlap
Determine if two triangles overlap
Determining if two triangles in the same plane overlap is an important topic in collision detection. Task Determine which of these pairs of triangles overlap in 2D:   (0,0),(5,0),(0,5)     and   (0,0),(5,0),(0,6)   (0,0),(0,5),(5,0)     and   (0,0),(0,5),(5,0)   (0,0),(5,0),(0,5)     and   (-10,0),(-5,0),(-1,6)...
#Go
Go
package main   import "fmt"   type point struct { x, y float64 }   func (p point) String() string { return fmt.Sprintf("(%.1f, %.1f)", p.x, p.y) }   type triangle struct { p1, p2, p3 point }   func (t *triangle) String() string { return fmt.Sprintf("Triangle %s, %s, %s", t.p1, t.p2, t.p3) }   func (t *t...
http://rosettacode.org/wiki/Delete_a_file
Delete a file
Task Delete a file called "input.txt" and delete a directory called "docs". This should be done twice: once "here", i.e. in the current working directory and once in the filesystem root.
#AWK
AWK
system("rm input.txt") system("rm /input.txt") system("rm -rf docs") system("rm -rf /docs")
http://rosettacode.org/wiki/Delete_a_file
Delete a file
Task Delete a file called "input.txt" and delete a directory called "docs". This should be done twice: once "here", i.e. in the current working directory and once in the filesystem root.
#Axe
Axe
DelVar "appvINPUT"
http://rosettacode.org/wiki/Determinant_and_permanent
Determinant and permanent
For a given matrix, return the determinant and the permanent of the matrix. The determinant is given by det ( A ) = ∑ σ sgn ⁡ ( σ ) ∏ i = 1 n M i , σ i {\displaystyle \det(A)=\sum _{\sigma }\operatorname {sgn}(\sigma )\prod _{i=1}^{n}M_{i,\sigma _{i}}} while the permanent is given by ...
#FunL
FunL
def sgn( p ) = product( (if s(0) < s(1) xor i(0) < i(1) then -1 else 1) | (s, i) <- p.combinations(2).zip( (0:p.length()).combinations(2) ) )   def perm( m ) = sum( product(m(i, sigma(i)) | i <- 0:m.length()) | sigma <- (0:m.length()).permutations() )   def det( m ) = sum( sgn(sigma)*product(m(i, sigma(i)) | i <- 0:m.l...
http://rosettacode.org/wiki/Determinant_and_permanent
Determinant and permanent
For a given matrix, return the determinant and the permanent of the matrix. The determinant is given by det ( A ) = ∑ σ sgn ⁡ ( σ ) ∏ i = 1 n M i , σ i {\displaystyle \det(A)=\sum _{\sigma }\operatorname {sgn}(\sigma )\prod _{i=1}^{n}M_{i,\sigma _{i}}} while the permanent is given by ...
#GLSL
GLSL
  mat4 m1 = mat3(1, 2, 3, 4, 5, 6, 7, 8 9,10,11,12, 13,14,15,16);   float d = det(m1);  
http://rosettacode.org/wiki/Detect_division_by_zero
Detect division by zero
Task Write a function to detect a   divide by zero error   without checking if the denominator is zero.
#Common_Lisp
Common Lisp
(handler-case (/ x y) (division-by-zero () (format t "division by zero caught!~%")))
http://rosettacode.org/wiki/Detect_division_by_zero
Detect division by zero
Task Write a function to detect a   divide by zero error   without checking if the denominator is zero.
#D
D
import std.stdio, std.string, std.math, std.traits;   string divCheck(T)(in T numer, in T denom) if (isIntegral!T || isFloatingPoint!T) { Unqual!(typeof(numer / denom)) result; string msg;   static if (isIntegral!T) { try { result = numer / denom; } catch(Error e) { m...
http://rosettacode.org/wiki/Determine_if_a_string_is_numeric
Determine if a string is numeric
Task Create a boolean function which takes in a string and tells whether it is a numeric string (floating point and negative numbers included) in the syntax the language uses for numeric literals or numbers converted from strings. Other tasks related to string operations: Metrics Array length String length Cop...
#Burlesque
Burlesque
  ps^^-]to{"Int""Double"}\/~[\/L[1==?*  
http://rosettacode.org/wiki/Determine_if_a_string_is_numeric
Determine if a string is numeric
Task Create a boolean function which takes in a string and tells whether it is a numeric string (floating point and negative numbers included) in the syntax the language uses for numeric literals or numbers converted from strings. Other tasks related to string operations: Metrics Array length String length Cop...
#C
C
#include <ctype.h> #include <stdlib.h> int isNumeric (const char * s) { if (s == NULL || *s == '\0' || isspace(*s)) return 0; char * p; strtod (s, &p); return *p == '\0'; }
http://rosettacode.org/wiki/Determine_if_a_string_has_all_unique_characters
Determine if a string has all unique characters
Task Given a character string   (which may be empty, or have a length of zero characters):   create a function/procedure/routine to:   determine if all the characters in the string are unique   indicate if or which character is duplicated and where   display each string and its length   (as the strings are being ...
#Delphi
Delphi
  program Determine_if_a_string_has_all_unique_characters;   {$APPTYPE CONSOLE}   uses System.SysUtils;   procedure string_has_repeated_character(str: string); var len, i, j: Integer; begin len := length(str); Writeln('input: \', str, '\, length: ', len); for i := 1 to len - 1 do begin for j := i + 1 to...
http://rosettacode.org/wiki/Determine_if_a_string_is_collapsible
Determine if a string is collapsible
Determine if a character string is   collapsible. And if so,   collapse the string   (by removing   immediately repeated   characters). If a character string has   immediately repeated   character(s),   the repeated characters are to be deleted (removed),   but not the primary (1st) character(s). An   immediatel...
#Java
Java
  // Title: Determine if a string is collapsible   public class StringCollapsible {   public static void main(String[] args) { for ( String s : new String[] { "", "\"If I were two-faced, would I be wearing this one?\" --- Abraham Lincoln ", "..111111111111111111...
http://rosettacode.org/wiki/Determine_if_a_string_has_all_the_same_characters
Determine if a string has all the same characters
Task Given a character string   (which may be empty, or have a length of zero characters):   create a function/procedure/routine to:   determine if all the characters in the string are the same   indicate if or which character is different from the previous character   display each string and its length   (as the...
#FreeBASIC
FreeBASIC
dim as string s, nxt   input "Enter string: ", s   if len(s)<2 then 'A string with one or zero characters passes by default print "All characters are the same." end end if   dim as ubyte i   for i = 1 to len(s)-1 nxt = mid(s, i+1, 1) if mid(s, i, 1)<>nxt then 'if any character differs from the prev...
http://rosettacode.org/wiki/Determine_if_a_string_has_all_the_same_characters
Determine if a string has all the same characters
Task Given a character string   (which may be empty, or have a length of zero characters):   create a function/procedure/routine to:   determine if all the characters in the string are the same   indicate if or which character is different from the previous character   display each string and its length   (as the...
#Go
Go
package main   import "fmt"   func analyze(s string) { chars := []rune(s) le := len(chars) fmt.Printf("Analyzing %q which has a length of %d:\n", s, le) if le > 1 { for i := 1; i < le; i++ { if chars[i] != chars[i-1] { fmt.Println(" Not all characters in the string a...
http://rosettacode.org/wiki/Dining_philosophers
Dining philosophers
The dining philosophers problem illustrates non-composability of low-level synchronization primitives like semaphores. It is a modification of a problem posed by Edsger Dijkstra. Five philosophers, Aristotle, Kant, Spinoza, Marx, and Russell (the tasks) spend their time thinking and eating spaghetti. They eat at a rou...
#Modula-3
Modula-3
MODULE DiningPhilosophers EXPORTS Main;   IMPORT IO, Random, Thread;   CONST   PartySize = 5; (* modify for more/fewer philosophers *)   TYPE   Closure = Thread.Closure OBJECT (* thread information *) which: [1..PartySize]; (* identifies the thread *) OVERRIDES apply := Live; (* procedure to execute *) ...
http://rosettacode.org/wiki/Discordian_date
Discordian date
Task Convert a given date from the   Gregorian calendar   to the   Discordian calendar.
#Maple
Maple
convertDiscordian := proc(year, month, day) local days31, days30, daysThisYear, i, dYear, dMonth, dDay, seasons, week, dayOfWeek; days31 := [1, 3, 5, 7, 8, 10, 12]; days30 := [4, 6, 9, 11]; if month < 1 or month >12 then error "Invalid month: %1", month; end if; if (member(month, days31) and day > 31) or (membe...
http://rosettacode.org/wiki/Dijkstra%27s_algorithm
Dijkstra's algorithm
This task has been clarified. Its programming examples are in need of review to ensure that they still fit the requirements of the task. Dijkstra's algorithm, conceived by Dutch computer scientist Edsger Dijkstra in 1956 and published in 1959, is a graph search algorithm that solves the single-source shortest path pro...
#Nim
Nim
  # Dijkstra algorithm.   from algorithm import reverse import sets import strformat import tables   type Edge = tuple[src, dst: string; cost: int] Graph = object vertices: HashSet[string] neighbours: Table[string, seq[tuple[dst: string, cost: float]]]   #----------------------------------------------------...
http://rosettacode.org/wiki/Digital_root
Digital root
The digital root, X {\displaystyle X} , of a number, n {\displaystyle n} , is calculated: find X {\displaystyle X} as the sum of the digits of n {\displaystyle n} find a new X {\displaystyle X} by summing the digits of X {\displaystyle X} , repeating until X {\displ...
#Haskell
Haskell
import Data.Bifunctor (bimap) import Data.List (unfoldr) import Data.Tuple (swap)   digSum :: Int -> Int -> Int digSum base = sum . unfoldr f where f 0 = Nothing f n = Just (swap (quotRem n base))   digRoot :: Int -> Int -> (Int, Int) digRoot base = head . dropWhile ((>= base) . snd) . iterate (bimap succ...
http://rosettacode.org/wiki/Digital_root/Multiplicative_digital_root
Digital root/Multiplicative digital root
The multiplicative digital root (MDR) and multiplicative persistence (MP) of a number, n {\displaystyle n} , is calculated rather like the Digital root except digits are multiplied instead of being added: Set m {\displaystyle m} to n {\displaystyle n} and i {\displaystyle i} to 0 ...
#Scala
Scala
import Stream._   object MDR extends App {   def mdr(x: BigInt, base: Int = 10): (BigInt, Long) = { def multiplyDigits(x: BigInt): BigInt = ((x.toString(base) map (_.asDigit)) :\ BigInt(1))(_*_) def loop(p: BigInt, c: Long): (BigInt, Long) = if (p < base) (p, c) else loop(multiplyDigits(p), c+1) loop(mult...
http://rosettacode.org/wiki/Dinesman%27s_multiple-dwelling_problem
Dinesman's multiple-dwelling problem
Task Solve Dinesman's multiple dwelling problem but in a way that most naturally follows the problem statement given below. Solutions are allowed (but not required) to parse and interpret the problem text, but should remain flexible and should state what changes to the problem text are allowed. Flexibility and ease of...
#Perl
Perl
use strict; use warnings; use feature <state say>; use List::Util 1.33 qw(pairmap); use Algorithm::Permute qw(permute);   our %predicates = ( # | object | sprintf format for Perl expression | # --------------------+-----------+------------------------------------+ 'on bottom' => [ ''...
http://rosettacode.org/wiki/Dot_product
Dot product
Task Create a function/use an in-built function, to compute the   dot product,   also known as the   scalar product   of two vectors. If possible, make the vectors of arbitrary length. As an example, compute the dot product of the vectors:   [1,  3, -5]     and   [4, -2, -1] If implementing the dot ...
#Haskell
Haskell
dotp :: Num a => [a] -> [a] -> a dotp a b | length a == length b = sum (zipWith (*) a b) | otherwise = error "Vector sizes must match"   main = print $ dotp [1, 3, -5] [4, -2, -1] -- prints 3
http://rosettacode.org/wiki/Determine_if_a_string_is_squeezable
Determine if a string is squeezable
Determine if a character string is   squeezable. And if so,   squeeze the string   (by removing any number of a   specified   immediately repeated   character). This task is very similar to the task     Determine if a character string is collapsible     except that only a specified character is   squeezed   instead...
#jq
jq
# Assume $c is specified as a single character correctly def squeeze($c): gsub("[\($c)]+"; $c);   def Guillemets: "«««\(.)»»»";   def Squeeze(s; $c): "Squeeze character: \($c)", (s | "Original: \(Guillemets) has length \(length)", (squeeze($c) | "result is \(Guillemets) with length \(length)")), "";
http://rosettacode.org/wiki/Determine_if_a_string_is_squeezable
Determine if a string is squeezable
Determine if a character string is   squeezable. And if so,   squeeze the string   (by removing any number of a   specified   immediately repeated   character). This task is very similar to the task     Determine if a character string is collapsible     except that only a specified character is   squeezed   instead...
#J_2
J
NB. Note |.!.1 here instead of the APL version's 1 , }. to more elegantly handle the null case in J sq =: ] #~ ~: +. _1 |.!.1 ] ~: 1 |. ]
http://rosettacode.org/wiki/Deming%27s_Funnel
Deming's Funnel
W Edwards Deming was an American statistician and management guru who used physical demonstrations to illuminate his teachings. In one demonstration Deming repeatedly dropped marbles through a funnel at a target, marking where they landed, and observing the resulting pattern. He applied a sequence of "rules" to try to ...
#Julia
Julia
# Run from Julia REPL to see the plots. using Statistics, Distributions, Plots   const racket_xdata = [-0.533, 0.270, 0.859, -0.043, -0.205, -0.127, -0.071, 0.275, 1.251, -0.231, -0.401, 0.269, 0.491, 0.951, 1.150, 0.001, -0.382, 0.161, 0.915, 2.080, -2.337, 0.034, -0.126, 0.014, 0.709, 0.129, -1.093, ...
http://rosettacode.org/wiki/Deming%27s_Funnel
Deming's Funnel
W Edwards Deming was an American statistician and management guru who used physical demonstrations to illuminate his teachings. In one demonstration Deming repeatedly dropped marbles through a funnel at a target, marking where they landed, and observing the resulting pattern. He applied a sequence of "rules" to try to ...
#Kotlin
Kotlin
// version 1.1.3   typealias Rule = (Double, Double) -> Double   val dxs = doubleArrayOf( -0.533, 0.270, 0.859, -0.043, -0.205, -0.127, -0.071, 0.275, 1.251, -0.231, -0.401, 0.269, 0.491, 0.951, 1.150, 0.001, -0.382, 0.161, 0.915, 2.080, -2.337, 0.034, -0.126, 0.014, 0.709, 0.129, -1.093...
http://rosettacode.org/wiki/Department_numbers
Department numbers
There is a highly organized city that has decided to assign a number to each of their departments:   police department   sanitation department   fire department Each department can have a number between   1   and   7   (inclusive). The three department numbers are to be unique (different from each other) and mu...
#ALGOL_W
ALGOL W
begin  % show possible department number allocations for police, sanitation and fire departments %  % the police department number must be even, all department numbers in the range 1 .. 7  %  % the sum of the department numbers must be 12  % integer MAX_DEPARTMENT...
http://rosettacode.org/wiki/Department_numbers
Department numbers
There is a highly organized city that has decided to assign a number to each of their departments:   police department   sanitation department   fire department Each department can have a number between   1   and   7   (inclusive). The three department numbers are to be unique (different from each other) and mu...
#APL
APL
'PSF'⍪(⊢(⌿⍨)((∪≡⊢)¨↓∧(0=2|1⌷[2]⊢)∧12=+/))↑,⍳3/7
http://rosettacode.org/wiki/Delegates
Delegates
A delegate is a helper object used by another object. The delegator may send the delegate certain messages, and provide a default implementation when there is no delegate or the delegate does not respond to a message. This pattern is heavily used in Cocoa framework on Mac OS X. See also wp:Delegation pattern. Objects ...
#Clojure
Clojure
(defprotocol Thing (thing [_]))   (defprotocol Operation (operation [_]))   (defrecord Delegator [delegate] Operation (operation [_] (try (thing delegate) (catch IllegalArgumentException e "default implementation"))))   (defrecord Delegate [] Thing (thing [_] "delegate implementation"))
http://rosettacode.org/wiki/Delegates
Delegates
A delegate is a helper object used by another object. The delegator may send the delegate certain messages, and provide a default implementation when there is no delegate or the delegate does not respond to a message. This pattern is heavily used in Cocoa framework on Mac OS X. See also wp:Delegation pattern. Objects ...
#CoffeeScript
CoffeeScript
  class Delegator operation: -> if @delegate and typeof (@delegate.thing) is "function" return @delegate.thing() "default implementation"   class Delegate thing: -> "Delegate Implementation"   testDelegator = -> # Delegator with no delegate. a = new Delegator() console.log a.operation()   ...
http://rosettacode.org/wiki/Determine_if_two_triangles_overlap
Determine if two triangles overlap
Determining if two triangles in the same plane overlap is an important topic in collision detection. Task Determine which of these pairs of triangles overlap in 2D:   (0,0),(5,0),(0,5)     and   (0,0),(5,0),(0,6)   (0,0),(0,5),(5,0)     and   (0,0),(0,5),(5,0)   (0,0),(5,0),(0,5)     and   (-10,0),(-5,0),(-1,6)...
#Groovy
Groovy
import java.util.function.BiFunction   class TriangleOverlap { private static class Pair { double first double second   Pair(double first, double second) { this.first = first this.second = second }   @Override String toString() { re...
http://rosettacode.org/wiki/Delete_a_file
Delete a file
Task Delete a file called "input.txt" and delete a directory called "docs". This should be done twice: once "here", i.e. in the current working directory and once in the filesystem root.
#BASIC
BASIC
  KILL "INPUT.TXT" KILL "C:\INPUT.TXT" SHELL "RMDIR /S /Q DIR" SHELL "RMDIR /S /Q C:\DIR"  
http://rosettacode.org/wiki/Delete_a_file
Delete a file
Task Delete a file called "input.txt" and delete a directory called "docs". This should be done twice: once "here", i.e. in the current working directory and once in the filesystem root.
#Batch_File
Batch File
del input.txt rd /s /q docs   del \input.txt rd /s /q \docs
http://rosettacode.org/wiki/Determinant_and_permanent
Determinant and permanent
For a given matrix, return the determinant and the permanent of the matrix. The determinant is given by det ( A ) = ∑ σ sgn ⁡ ( σ ) ∏ i = 1 n M i , σ i {\displaystyle \det(A)=\sum _{\sigma }\operatorname {sgn}(\sigma )\prod _{i=1}^{n}M_{i,\sigma _{i}}} while the permanent is given by ...
#Go
Go
package main   import ( "fmt" "permute" )   func determinant(m [][]float64) (d float64) { p := make([]int, len(m)) for i := range p { p[i] = i } it := permute.Iter(p) for s := it(); s != 0; s = it() { pr := 1. for i, σ := range p { pr *= m[i][σ] } ...
http://rosettacode.org/wiki/Detect_division_by_zero
Detect division by zero
Task Write a function to detect a   divide by zero error   without checking if the denominator is zero.
#Delphi
Delphi
program DivideByZero;   {$APPTYPE CONSOLE}   uses SysUtils;   var a, b: Integer; begin a := 1; b := 0; try WriteLn(a / b); except on e: EZeroDivide do Writeln(e.Message); end; end.
http://rosettacode.org/wiki/Detect_division_by_zero
Detect division by zero
Task Write a function to detect a   divide by zero error   without checking if the denominator is zero.
#D.C3.A9j.C3.A0_Vu
Déjà Vu
divcheck x y: true try: drop / x y catch value-error: not   if divcheck 1 0:  !print "Okay" else:  !print "Division by zero"
http://rosettacode.org/wiki/Determine_if_a_string_is_numeric
Determine if a string is numeric
Task Create a boolean function which takes in a string and tells whether it is a numeric string (floating point and negative numbers included) in the syntax the language uses for numeric literals or numbers converted from strings. Other tasks related to string operations: Metrics Array length String length Cop...
#C.23
C#
public static bool IsNumeric(string s) { double Result; return double.TryParse(s, out Result); // TryParse routines were added in Framework version 2.0. }   string value = "123"; if (IsNumeric(value)) { // do something }
http://rosettacode.org/wiki/Determine_if_a_string_is_numeric
Determine if a string is numeric
Task Create a boolean function which takes in a string and tells whether it is a numeric string (floating point and negative numbers included) in the syntax the language uses for numeric literals or numbers converted from strings. Other tasks related to string operations: Metrics Array length String length Cop...
#C.2B.2B
C++
#include <sstream> // for istringstream   using namespace std;   bool isNumeric( const char* pszInput, int nNumberBase ) { istringstream iss( pszInput );   if ( nNumberBase == 10 ) { double dTestSink; iss >> dTestSink; } else if ( nNumberBase == 8 || nNumberBase == 16 ) { int nTestSink; iss >> ( ( nNumber...
http://rosettacode.org/wiki/Determine_if_a_string_has_all_unique_characters
Determine if a string has all unique characters
Task Given a character string   (which may be empty, or have a length of zero characters):   create a function/procedure/routine to:   determine if all the characters in the string are unique   indicate if or which character is duplicated and where   display each string and its length   (as the strings are being ...
#Erlang
Erlang
  -module(string_examples). -export([all_unique/1, all_unique_examples/0]).   all_unique(String) -> CharPosPairs = lists:zip(String, lists:seq(1, length(String))), Duplicates = [{Char1, Pos1, Pos2} || {Char1, Pos1} <- CharPosPairs, {Char2, Pos2} <- CharPosPairs, ...
http://rosettacode.org/wiki/Determine_if_a_string_is_collapsible
Determine if a string is collapsible
Determine if a character string is   collapsible. And if so,   collapse the string   (by removing   immediately repeated   characters). If a character string has   immediately repeated   character(s),   the repeated characters are to be deleted (removed),   but not the primary (1st) character(s). An   immediatel...
#JavaScript
JavaScript
  String.prototype.collapse = function() { let str = this; for (let i = 0; i < str.length; i++) { while (str[i] == str[i+1]) str = str.substr(0,i) + str.substr(i+1); } return str; }   // testing let strings = [ '', '"If I were two-faced, would I be wearing this one?" --- Abraham Lincoln ', '..11111111...
http://rosettacode.org/wiki/Determine_if_a_string_is_collapsible
Determine if a string is collapsible
Determine if a character string is   collapsible. And if so,   collapse the string   (by removing   immediately repeated   characters). If a character string has   immediately repeated   character(s),   the repeated characters are to be deleted (removed),   but not the primary (1st) character(s). An   immediatel...
#jq
jq
# Input: an array # Output: a stream def uniq: foreach .[] as $x ({x:nan, y:.[0]}; {x:$x, y:.x}; select(.x != .y) | .x);   def collapse: explode | [uniq] | implode;
http://rosettacode.org/wiki/Determine_if_a_string_has_all_the_same_characters
Determine if a string has all the same characters
Task Given a character string   (which may be empty, or have a length of zero characters):   create a function/procedure/routine to:   determine if all the characters in the string are the same   indicate if or which character is different from the previous character   display each string and its length   (as the...
#Groovy
Groovy
class Main { static void main(String[] args) { String[] tests = ["", " ", "2", "333", ".55", "tttTTT", "4444 444k"] for (String s : tests) { analyze(s) } }   static void analyze(String s) { println("Examining [$s] which has a length of ${s.length()}") if...
http://rosettacode.org/wiki/Dining_philosophers
Dining philosophers
The dining philosophers problem illustrates non-composability of low-level synchronization primitives like semaphores. It is a modification of a problem posed by Edsger Dijkstra. Five philosophers, Aristotle, Kant, Spinoza, Marx, and Russell (the tasks) spend their time thinking and eating spaghetti. They eat at a rou...
#Nim
Nim
import threadpool, locks, math, os, random # to call randomize() as a seed, need to import random module randomize()   type Philosopher = ref object name: string food: string forkLeft, forkRight: int   const n = 5 names = ["Aristotle", "Kant", "Spinoza", "Marx", "Russell"] foods = [" rat poison", " cockroac...
http://rosettacode.org/wiki/Discordian_date
Discordian date
Task Convert a given date from the   Gregorian calendar   to the   Discordian calendar.
#Mathematica_.2F_Wolfram_Language
Mathematica / Wolfram Language
DiscordianDate[y_, m_, d_] := Module[{year = ToString[y + 1166], month = m, day = d},   DMONTHS = {"Chaos", "Discord", "Confusion", "Bureaucracy", "The Aftermath"}; DDAYS = {"Sweetmorn", "Boomtime", "Pungenday", "Prickle-Prickle", "Setting Orange"}; DayOfYear = DateDifference[{y} ,{y, m, d}] + 1; LeapYearQ = (M...
http://rosettacode.org/wiki/Dijkstra%27s_algorithm
Dijkstra's algorithm
This task has been clarified. Its programming examples are in need of review to ensure that they still fit the requirements of the task. Dijkstra's algorithm, conceived by Dutch computer scientist Edsger Dijkstra in 1956 and published in 1959, is a graph search algorithm that solves the single-source shortest path pro...
#OCaml
OCaml
let list_vertices graph = List.fold_left (fun acc ((a, b), _) -> let acc = if List.mem b acc then acc else b::acc in let acc = if List.mem a acc then acc else a::acc in acc ) [] graph   let neighbors v = List.fold_left (fun acc ((a, b), d) -> if a = v then (b, d)::acc else acc ) []   let remove_...
http://rosettacode.org/wiki/Digital_root
Digital root
The digital root, X {\displaystyle X} , of a number, n {\displaystyle n} , is calculated: find X {\displaystyle X} as the sum of the digits of n {\displaystyle n} find a new X {\displaystyle X} by summing the digits of X {\displaystyle X} , repeating until X {\displ...
#Huginn
Huginn
main( argv_ ) { if ( size( argv_ ) < 2 ) { throw Exception( "usage: digital-root {NUM}" ); } n = argv_[1]; if ( ( size( n ) == 0 ) || ( n.find_other_than( "0123456789" ) >= 0 ) ) { throw Exception( "{} is not a number".format( n ) ); } shift = integer( '0' ) + 1; acc = 0; for ( d : n ) { acc = 1 + ( acc +...
http://rosettacode.org/wiki/Digital_root
Digital root
The digital root, X {\displaystyle X} , of a number, n {\displaystyle n} , is calculated: find X {\displaystyle X} as the sum of the digits of n {\displaystyle n} find a new X {\displaystyle X} by summing the digits of X {\displaystyle X} , repeating until X {\displ...
#Icon_and_Unicon
Icon and Unicon
procedure main(A) every m := n := integer(!A) do { ap := 0 while (*n > 1) do (ap +:= 1, n := sumdigits(n)) write(m," has additive persistence of ",ap," and digital root of ",n) } end   procedure sumdigits(n) s := 0 n ? while s +:= move(1) return s end
http://rosettacode.org/wiki/Digital_root/Multiplicative_digital_root
Digital root/Multiplicative digital root
The multiplicative digital root (MDR) and multiplicative persistence (MP) of a number, n {\displaystyle n} , is calculated rather like the Digital root except digits are multiplied instead of being added: Set m {\displaystyle m} to n {\displaystyle n} and i {\displaystyle i} to 0 ...
#Scheme
Scheme
; Convert an integer into a list of its digits.   (define integer->list (lambda (integer) (let loop ((list '()) (int integer)) (if (< int 10) (cons int list) (loop (cons (remainder int 10) list) (quotient int 10))))))   ; Return the product of the digits of an integer.   (define integer-prod...
http://rosettacode.org/wiki/Dinesman%27s_multiple-dwelling_problem
Dinesman's multiple-dwelling problem
Task Solve Dinesman's multiple dwelling problem but in a way that most naturally follows the problem statement given below. Solutions are allowed (but not required) to parse and interpret the problem text, but should remain flexible and should state what changes to the problem text are allowed. Flexibility and ease of...
#Phix
Phix
with javascript_semantics enum Baker, Cooper, Fletcher, Miller, Smith constant names={"Baker","Cooper","Fletcher","Miller","Smith"} procedure test(sequence flats) if flats[Baker]!=5 and flats[Cooper]!=1 and not find(flats[Fletcher],{1,5}) and flats[Miller]>flats[Cooper] and abs(flats[Smith]-flats[...
http://rosettacode.org/wiki/Dot_product
Dot product
Task Create a function/use an in-built function, to compute the   dot product,   also known as the   scalar product   of two vectors. If possible, make the vectors of arbitrary length. As an example, compute the dot product of the vectors:   [1,  3, -5]     and   [4, -2, -1] If implementing the dot ...
#Hoon
Hoon
|= [a=(list @sd) b=(list @sd)] =| sum=@sd |-  ?: |(?=(~ a) ?=(~ b)) sum $(a t.a, b t.b, sum (sum:si sum (pro:si i.a i.b)))
http://rosettacode.org/wiki/Dot_product
Dot product
Task Create a function/use an in-built function, to compute the   dot product,   also known as the   scalar product   of two vectors. If possible, make the vectors of arbitrary length. As an example, compute the dot product of the vectors:   [1,  3, -5]     and   [4, -2, -1] If implementing the dot ...
#Hy
Hy
(defn dotp [a b] (assert (= (len a) (len b))) (sum (genexpr (* aterm bterm) [(, aterm bterm) (zip a b)])))   (assert (= 3 (dotp [1 3 -5] [4 -2 -1])))
http://rosettacode.org/wiki/Determine_if_a_string_is_squeezable
Determine if a string is squeezable
Determine if a character string is   squeezable. And if so,   squeeze the string   (by removing any number of a   specified   immediately repeated   character). This task is very similar to the task     Determine if a character string is collapsible     except that only a specified character is   squeezed   instead...
#Julia
Julia
const teststringpairs = [ ("", ' '), (""""If I were two-faced, would I be wearing this one?" --- Abraham Lincoln """, '-'), ("..1111111111111111111111111111111111111111111111111111111111111117777888", '7'), ("""I never give 'em hell, I just tell the truth, and they think it's hell. """, '.'), (" ...
http://rosettacode.org/wiki/Determine_if_a_string_is_squeezable
Determine if a string is squeezable
Determine if a character string is   squeezable. And if so,   squeeze the string   (by removing any number of a   specified   immediately repeated   character). This task is very similar to the task     Determine if a character string is collapsible     except that only a specified character is   squeezed   instead...
#Kotlin
Kotlin
fun main() { val testStrings = arrayOf( "", "\"If I were two-faced, would I be wearing this one?\" --- Abraham Lincoln ", "..1111111111111111111111111111111111111111111111111111111111111117777888", "I never give 'em hell, I just tell the truth, and they think it's hell. ", " ...
http://rosettacode.org/wiki/Deming%27s_Funnel
Deming's Funnel
W Edwards Deming was an American statistician and management guru who used physical demonstrations to illuminate his teachings. In one demonstration Deming repeatedly dropped marbles through a funnel at a target, marking where they landed, and observing the resulting pattern. He applied a sequence of "rules" to try to ...
#Mathematica.2FWolfram_Language
Mathematica/Wolfram Language
dxs = {-0.533, 0.27, 0.859, -0.043, -0.205, -0.127, -0.071, 0.275, 1.251, -0.231, -0.401, 0.269, 0.491, 0.951, 1.15, 0.001, -0.382, 0.161, 0.915, 2.08, -2.337, 0.034, -0.126, 0.014, 0.709, 0.129, -1.093, -0.483, -1.193, 0.02, -0.051, 0.047, -0.095, 0.695, 0.34, -0.182, 0.287, 0.213, -0.423, -0.021, -0.1...
http://rosettacode.org/wiki/Deming%27s_Funnel
Deming's Funnel
W Edwards Deming was an American statistician and management guru who used physical demonstrations to illuminate his teachings. In one demonstration Deming repeatedly dropped marbles through a funnel at a target, marking where they landed, and observing the resulting pattern. He applied a sequence of "rules" to try to ...
#Stretch_1
Stretch 1
  RadiusDistribution = NormalDistribution[0, 1]; AngleDistribution = UniformDistribution[{0, Pi}];   (*Mathematica has built in transformation functions, but this seems clearer given the way the instructions were written.*) ToCartesian[{r_, a_}] := ToCartesian[{Abs@r, a - Pi}] /; Negative[r]; ToCartesian[{r_, a_}] := F...
http://rosettacode.org/wiki/Department_numbers
Department numbers
There is a highly organized city that has decided to assign a number to each of their departments:   police department   sanitation department   fire department Each department can have a number between   1   and   7   (inclusive). The three department numbers are to be unique (different from each other) and mu...
#AppleScript
AppleScript
on run script on |λ|(x) script on |λ|(y) script on |λ|(z) if y ≠ z and 1 ≤ z and z ≤ 7 then {{x, y, z} as string} else ...
http://rosettacode.org/wiki/Delegates
Delegates
A delegate is a helper object used by another object. The delegator may send the delegate certain messages, and provide a default implementation when there is no delegate or the delegate does not respond to a message. This pattern is heavily used in Cocoa framework on Mac OS X. See also wp:Delegation pattern. Objects ...
#Common_Lisp
Common Lisp
(defgeneric thing (object) (:documentation "Thing the object."))   (defmethod thing (object) "default implementation")   (defclass delegator () ((delegate :initarg :delegate :reader delegator-delegate)))   (defmethod thing ((delegator delegator)) "If delegator has a delegate, invoke thing on the delegat...
http://rosettacode.org/wiki/Delegates
Delegates
A delegate is a helper object used by another object. The delegator may send the delegate certain messages, and provide a default implementation when there is no delegate or the delegate does not respond to a message. This pattern is heavily used in Cocoa framework on Mac OS X. See also wp:Delegation pattern. Objects ...
#D
D
class Delegator { string delegate() hasDelegate;   string operation() { if (hasDelegate is null) return "Default implementation"; return hasDelegate(); }   typeof(this) setDg(string delegate() dg) { hasDelegate = dg; return this; } }   void main() { im...
http://rosettacode.org/wiki/Determine_if_two_triangles_overlap
Determine if two triangles overlap
Determining if two triangles in the same plane overlap is an important topic in collision detection. Task Determine which of these pairs of triangles overlap in 2D:   (0,0),(5,0),(0,5)     and   (0,0),(5,0),(0,6)   (0,0),(0,5),(5,0)     and   (0,0),(0,5),(5,0)   (0,0),(5,0),(0,5)     and   (-10,0),(-5,0),(-1,6)...
#Haskell
Haskell
isOverlapping :: Triangle Double -> Triangle Double -> Bool isOverlapping t1 t2 = vertexInside || midLineInside where vertexInside = any (isInside t1) (vertices t2) || any (isInside t2) (vertices t1)   isInside t = (Outside /=) . overlapping t   midLineInside = any (\p -> isInside t1 p &...
http://rosettacode.org/wiki/Delete_a_file
Delete a file
Task Delete a file called "input.txt" and delete a directory called "docs". This should be done twice: once "here", i.e. in the current working directory and once in the filesystem root.
#C
C
#include <stdio.h>   int main() { remove("input.txt"); remove("/input.txt"); remove("docs"); remove("/docs"); return 0; }
http://rosettacode.org/wiki/Delete_a_file
Delete a file
Task Delete a file called "input.txt" and delete a directory called "docs". This should be done twice: once "here", i.e. in the current working directory and once in the filesystem root.
#C.23
C#
using System; using System.IO;   namespace RosettaCode { class Program { static void Main() { try { File.Delete("input.txt"); Directory.Delete("docs"); File.Delete(@"\input.txt"); Directory.Delete(@"\docs"); } catch (Exc...
http://rosettacode.org/wiki/Determinant_and_permanent
Determinant and permanent
For a given matrix, return the determinant and the permanent of the matrix. The determinant is given by det ( A ) = ∑ σ sgn ⁡ ( σ ) ∏ i = 1 n M i , σ i {\displaystyle \det(A)=\sum _{\sigma }\operatorname {sgn}(\sigma )\prod _{i=1}^{n}M_{i,\sigma _{i}}} while the permanent is given by ...
#Haskell
Haskell
sPermutations :: [a] -> [([a], Int)] sPermutations = flip zip (cycle [1, -1]) . foldl aux [[]] where aux items x = do (f, item) <- zip (cycle [reverse, id]) items f (insertEv x item) insertEv x [] = [[x]] insertEv x l@(y:ys) = (x : l) : ((y :) <$>) (insertEv x ys)   elemPos :: [[a]] -> Int -> ...
http://rosettacode.org/wiki/Detect_division_by_zero
Detect division by zero
Task Write a function to detect a   divide by zero error   without checking if the denominator is zero.
#E
E
def divide(numerator, denominator) { def floatQuotient := numerator / denominator if (floatQuotient.isNaN() || floatQuotient.isInfinite()) { return ["zero denominator"] } else { return ["ok", floatQuotient] } }
http://rosettacode.org/wiki/Detect_division_by_zero
Detect division by zero
Task Write a function to detect a   divide by zero error   without checking if the denominator is zero.
#ECL
ECL
  DBZ(REAL8 Dividend,INTEGER8 Divisor) := Quotient/Divisor;   #option ('divideByZero', 'zero'); DBZ(10,0); //returns 0.0  
http://rosettacode.org/wiki/Determine_if_a_string_is_numeric
Determine if a string is numeric
Task Create a boolean function which takes in a string and tells whether it is a numeric string (floating point and negative numbers included) in the syntax the language uses for numeric literals or numbers converted from strings. Other tasks related to string operations: Metrics Array length String length Cop...
#CFScript
CFScript
isNumeric(42)
http://rosettacode.org/wiki/Determine_if_a_string_is_numeric
Determine if a string is numeric
Task Create a boolean function which takes in a string and tells whether it is a numeric string (floating point and negative numbers included) in the syntax the language uses for numeric literals or numbers converted from strings. Other tasks related to string operations: Metrics Array length String length Cop...
#Clojure
Clojure
(defn numeric? [s] (if-let [s (seq s)] (let [s (if (= (first s) \-) (next s) s) s (drop-while #(Character/isDigit %) s) s (if (= (first s) \.) (next s) s) s (drop-while #(Character/isDigit %) s)] (empty? s))))
http://rosettacode.org/wiki/Determine_if_a_string_has_all_unique_characters
Determine if a string has all unique characters
Task Given a character string   (which may be empty, or have a length of zero characters):   create a function/procedure/routine to:   determine if all the characters in the string are unique   indicate if or which character is duplicated and where   display each string and its length   (as the strings are being ...
#F.23
F#
  // Determine if a string has all unique characters. Nigel Galloway: June 9th., 2020 let fN (n:string)=n.ToCharArray()|>Array.mapi(fun n g->(n,g))|>Array.groupBy(fun (_,n)->n)|>Array.filter(fun(_,n)->n.Length>1)   let allUnique n=match fN n with g when g.Length=0->printfn "All charcters in <<<%s>>> (l...
http://rosettacode.org/wiki/Determine_if_a_string_is_collapsible
Determine if a string is collapsible
Determine if a character string is   collapsible. And if so,   collapse the string   (by removing   immediately repeated   characters). If a character string has   immediately repeated   character(s),   the repeated characters are to be deleted (removed),   but not the primary (1st) character(s). An   immediatel...
#Julia
Julia
const teststrings = [ "", """"If I were two-faced, would I be wearing this one?" --- Abraham Lincoln """, "..1111111111111111111111111111111111111111111111111111111111111117777888", """I never give 'em hell, I just tell the truth, and they think it's hell. """, " ...
http://rosettacode.org/wiki/Determine_if_a_string_is_collapsible
Determine if a string is collapsible
Determine if a character string is   collapsible. And if so,   collapse the string   (by removing   immediately repeated   characters). If a character string has   immediately repeated   character(s),   the repeated characters are to be deleted (removed),   but not the primary (1st) character(s). An   immediatel...
#Kotlin
Kotlin
fun collapse(s: String): String { val cs = StringBuilder() var last: Char = 0.toChar() for (c in s) { if (c != last) { cs.append(c) last = c } } return cs.toString() }   fun main() { val strings = arrayOf( "", "\"If I were two-faced, would ...
http://rosettacode.org/wiki/Determine_if_a_string_has_all_the_same_characters
Determine if a string has all the same characters
Task Given a character string   (which may be empty, or have a length of zero characters):   create a function/procedure/routine to:   determine if all the characters in the string are the same   indicate if or which character is different from the previous character   display each string and its length   (as the...
#Haskell
Haskell
import Numeric (showHex) import Data.List (span) import Data.Char (ord)   inconsistentChar :: Eq a => [a] -> Maybe (Int, a) inconsistentChar [] = Nothing inconsistentChar xs@(x:_) = let (pre, post) = span (x ==) xs in if null post then Nothing else Just (length pre, head post)     --------------------...
http://rosettacode.org/wiki/Dining_philosophers
Dining philosophers
The dining philosophers problem illustrates non-composability of low-level synchronization primitives like semaphores. It is a modification of a problem posed by Edsger Dijkstra. Five philosophers, Aristotle, Kant, Spinoza, Marx, and Russell (the tasks) spend their time thinking and eating spaghetti. They eat at a rou...
#OxygenBasic
OxygenBasic
  '========================= class RoundTableWith5Seats '=========================    % hungry 0  % beingUsed 1  % putDown 0  % empty 0   sys fork[5], plate[5],chair[5],philosopher[5] sys first   method AddPasta() as sys function rand() as sys static seed=0x12345678 mov eax,seed ...
http://rosettacode.org/wiki/Discordian_date
Discordian date
Task Convert a given date from the   Gregorian calendar   to the   Discordian calendar.
#Nim
Nim
import times, strformat   const   DiscordianOrigin = -1166 SaintTibsDay = "St. Tib’s Day"   type   Season = enum sCha = (1, "Chaos"), sDis = "Discord", sCon = "Confusion", sBur = "Bureaucracy", sAft = "The Aftermath"   ErisianWeekDay = enum eSwe = "Sweetmorn", eBoo = "Boomtime", ePun = "Pungenday", ...
http://rosettacode.org/wiki/Dijkstra%27s_algorithm
Dijkstra's algorithm
This task has been clarified. Its programming examples are in need of review to ensure that they still fit the requirements of the task. Dijkstra's algorithm, conceived by Dutch computer scientist Edsger Dijkstra in 1956 and published in 1959, is a graph search algorithm that solves the single-source shortest path pro...
#PARI.2FGP
PARI/GP
shortestPath(G, startAt=1)={ my(n=#G[,1],dist=vector(n,i,9e99),prev=dist,Q=2^n-1); dist[startAt]=0; while(Q, my(t=vecmin(vecextract(dist,Q)),u); if(t==9e99, break); for(i=1,#v,if(dist[i]==t && bittest(Q,i-1), u=i; break)); Q-=1<<(u-1); for(i=1,n, if(!G[u,i],next); my(alt=dist[u]+G[u,i]); if (alt <...
http://rosettacode.org/wiki/Digital_root
Digital root
The digital root, X {\displaystyle X} , of a number, n {\displaystyle n} , is calculated: find X {\displaystyle X} as the sum of the digits of n {\displaystyle n} find a new X {\displaystyle X} by summing the digits of X {\displaystyle X} , repeating until X {\displ...
#J
J
digrot=: +/@(#.inv~&10)^:_ addper=: _1 + [: # +/@(#.inv~&10)^:a:
http://rosettacode.org/wiki/Digital_root
Digital root
The digital root, X {\displaystyle X} , of a number, n {\displaystyle n} , is calculated: find X {\displaystyle X} as the sum of the digits of n {\displaystyle n} find a new X {\displaystyle X} by summing the digits of X {\displaystyle X} , repeating until X {\displ...
#Java
Java
import java.math.BigInteger;   class DigitalRoot { public static int[] calcDigitalRoot(String number, int base) { BigInteger bi = new BigInteger(number, base); int additivePersistence = 0; if (bi.signum() < 0) bi = bi.negate(); BigInteger biBase = BigInteger.valueOf(base); while (bi.compar...
http://rosettacode.org/wiki/Digital_root/Multiplicative_digital_root
Digital root/Multiplicative digital root
The multiplicative digital root (MDR) and multiplicative persistence (MP) of a number, n {\displaystyle n} , is calculated rather like the Digital root except digits are multiplied instead of being added: Set m {\displaystyle m} to n {\displaystyle n} and i {\displaystyle i} to 0 ...
#Sidef
Sidef
func mdroot(n) { var (mdr, persist) = (n, 0) while (mdr >= 10) { mdr = mdr.digits.prod ++persist } [mdr, persist] }   say "Number: MDR MP\n====== === ==" [123321, 7739, 893, 899998].each{|n| "%6d: %3d %3d\n" \ .printf(n, mdroot(n)...) }   var counter = Hash()   Inf.times { ...
http://rosettacode.org/wiki/Dinesman%27s_multiple-dwelling_problem
Dinesman's multiple-dwelling problem
Task Solve Dinesman's multiple dwelling problem but in a way that most naturally follows the problem statement given below. Solutions are allowed (but not required) to parse and interpret the problem text, but should remain flexible and should state what changes to the problem text are allowed. Flexibility and ease of...
#Picat
Picat
import util. import cp.   dinesman_cp => println(dinesman_cp), N = 5, X = [Baker, Cooper, Fletcher, Miller, Smith], X :: 1..N,   all_different(X),    % Baker does not live on the fifth floor. Baker #!= 5,    % Cooper does not live on the first floor. Cooper #!= 1,    % Fletcher does not live...
http://rosettacode.org/wiki/Dot_product
Dot product
Task Create a function/use an in-built function, to compute the   dot product,   also known as the   scalar product   of two vectors. If possible, make the vectors of arbitrary length. As an example, compute the dot product of the vectors:   [1,  3, -5]     and   [4, -2, -1] If implementing the dot ...
#Icon_and_Unicon
Icon and Unicon
procedure main() write("a dot b := ",dotproduct([1, 3, -5],[4, -2, -1])) end   procedure dotproduct(a,b) #: return dot product of vectors a & b or error if *a ~= *b & type(a) == type(b) == "list" then runerr(205,a) # invalid value every (dp := 0) +:= a[i := 1 to *a] * b[i] return dp end
http://rosettacode.org/wiki/Determine_if_a_string_is_squeezable
Determine if a string is squeezable
Determine if a character string is   squeezable. And if so,   squeeze the string   (by removing any number of a   specified   immediately repeated   character). This task is very similar to the task     Determine if a character string is collapsible     except that only a specified character is   squeezed   instead...
#Lua
Lua
function squeezable(s, rune) print("squeeze: `" .. rune .. "`") print("old: <<<" .. s .. ">>>, length = " .. string.len(s))   local last = nil local le = 0 io.write("new: <<<") for c in s:gmatch"." do if c ~= last or c ~= rune then io.write(c) le = le + 1 ...
http://rosettacode.org/wiki/Determine_if_a_string_is_squeezable
Determine if a string is squeezable
Determine if a character string is   squeezable. And if so,   squeeze the string   (by removing any number of a   specified   immediately repeated   character). This task is very similar to the task     Determine if a character string is collapsible     except that only a specified character is   squeezed   instead...
#Mathematica_.2F_Wolfram_Language
Mathematica / Wolfram Language
ClearAll[Squeeze] Squeeze[s_String,sq_String]:=StringReplace[s,x:(sq..):>sq] s={ "", "\"If I were two-faced, would I be wearing this one?\" --- Abraham Lincoln", "..1111111111111111111111111111111111111111111111111111111111111117777888", "I never give 'em hell, I just tell the truth, and they think it's hell. ...