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http://rosettacode.org/wiki/Joystick_position
Joystick position
The task is to determine the joystick position and represent this on the display via a crosshair. For a centred joystick, the crosshair should appear in the centre of the screen. If the joystick is pushed left or right, then the cross hair should move left or right according to the extent that the joystick is pushed. ...
#Phix
Phix
without js -- Joystick library for Euphoria (Windows) -- /Mic, 2002 -- -- integer joy_init() -- returns the number of joysticks attached to the computer -- -- sequence joy_get_state(integer joy_num) -- returns the current state of joystick #joy_num (can be either 1 or 2). -- the format of the return sequence is: -- ...
http://rosettacode.org/wiki/K-d_tree
K-d tree
This page uses content from Wikipedia. The original article was at K-d tree. The list of authors can be seen in the page history. As with Rosetta Code, the text of Wikipedia is available under the GNU FDL. (See links for details on variance) A k-d tree (short for k-dimensional tree) is a space-partitioning data str...
#Tcl
Tcl
package require TclOO   oo::class create KDTree { variable t dim constructor {points} { set t [my Build 0 $points 0 end] set dim [llength [lindex $points 0]] } method Build {split exset from to} { set exset [lsort -index $split -real [lrange $exset $from $to]] if {![llength $exset]} {return 0} set ...
http://rosettacode.org/wiki/Knight%27s_tour
Knight's tour
Task Problem: you have a standard 8x8 chessboard, empty but for a single knight on some square. Your task is to emit a series of legal knight moves that result in the knight visiting every square on the chessboard exactly once. Note that it is not a requirement that the tour be "closed"; that is, the knight need not e...
#D
D
import std.stdio, std.algorithm, std.random, std.range, std.conv, std.typecons, std.typetuple;   int[N][N] knightTour(size_t N=8)(in string start) in { assert(start.length >= 2); } body { static struct P { int x, y; }   immutable P[8] moves = [P(2,1), P(1,2), P(-1,2), P(-2,1), ...
http://rosettacode.org/wiki/Knuth_shuffle
Knuth shuffle
The   Knuth shuffle   (a.k.a. the Fisher-Yates shuffle)   is an algorithm for randomly shuffling the elements of an array. Task Implement the Knuth shuffle for an integer array (or, if possible, an array of any type). Specification Given an array items with indices ranging from 0 to last, the algorithm can be d...
#DWScript
DWScript
procedure KnuthShuffle(a : array of Integer); var i, j, tmp : Integer; begin for i:=a.High downto 1 do begin j:=RandomInt(a.Length); tmp:=a[i]; a[i]:=a[j]; a[j]:=tmp; end; end;
http://rosettacode.org/wiki/K-means%2B%2B_clustering
K-means++ clustering
K-means++ clustering K-means This data was partitioned into 7 clusters using the K-means algorithm. The task is to implement the K-means++ algorithm. Produce a function which takes two arguments: the number of clusters K, and the dataset to classify. K is a positive integer and the dataset is a list of points in the C...
#Lua
Lua
    local function load_data(npoints, radius) -- Generate random data points -- local data = {} for i = 1,npoints do local ang = math.random() * (2.0 * math.pi) local rad = math.random() * radius data[i] = {x = math.cos(ang) * rad, y = math.sin(ang) * rad} end return data end   local function pr...
http://rosettacode.org/wiki/Kernighans_large_earthquake_problem
Kernighans large earthquake problem
Brian Kernighan, in a lecture at the University of Nottingham, described a problem on which this task is based. Problem You are given a a data file of thousands of lines; each of three `whitespace` separated fields: a date, a one word name and the magnitude of the event. Example lines from the file would be lines li...
#Ring
Ring
  # Project  : Kernighans large earthquake problem   load "stdlib.ring" nr = 0 equake = list(3) fn = "equake.txt" fp = fopen(fn,"r")   while not feof(fp) nr = nr + 1 equake[nr] = readline(fp) end fclose(fp) for n = 1 to len(equake) for m = 1 to len(equake[n]) if equake[n][m] = " " ...
http://rosettacode.org/wiki/Kernighans_large_earthquake_problem
Kernighans large earthquake problem
Brian Kernighan, in a lecture at the University of Nottingham, described a problem on which this task is based. Problem You are given a a data file of thousands of lines; each of three `whitespace` separated fields: a date, a one word name and the magnitude of the event. Example lines from the file would be lines li...
#Ruby
Ruby
ruby -nae "$F[2].to_f > 6 && print" data.txt
http://rosettacode.org/wiki/Kernighans_large_earthquake_problem
Kernighans large earthquake problem
Brian Kernighan, in a lecture at the University of Nottingham, described a problem on which this task is based. Problem You are given a a data file of thousands of lines; each of three `whitespace` separated fields: a date, a one word name and the magnitude of the event. Example lines from the file would be lines li...
#Rust
Rust
fn main() -> Result<(), Box<dyn std::error::Error>> { use std::io::{BufRead, BufReader};   for line in BufReader::new(std::fs::OpenOptions::new().read(true).open("data.txt")?).lines() { let line = line?;   let magnitude = line .split_whitespace() .nth(2) .and_...
http://rosettacode.org/wiki/Kernighans_large_earthquake_problem
Kernighans large earthquake problem
Brian Kernighan, in a lecture at the University of Nottingham, described a problem on which this task is based. Problem You are given a a data file of thousands of lines; each of three `whitespace` separated fields: a date, a one word name and the magnitude of the event. Example lines from the file would be lines li...
#Scala
Scala
scala.io.Source.fromFile("data.txt").getLines .map("\\s+".r.split(_)) .filter(_(2).toDouble > 6.0) .map(_.mkString("\t")) .foreach(println)
http://rosettacode.org/wiki/Julia_set
Julia set
Task Generate and draw a Julia set. Related tasks   Mandelbrot Set
#FreeBASIC
FreeBASIC
  #define pix 1./120 #define zero_x 320 #define zero_y 240 #define maxiter 250   type complex r as double i as double end type   operator + (x as complex, y as complex) as complex dim as complex ret ret.r = x.r + y.r ret.i = x.i + y.i return ret end operator   operator * (x as complex, y as comp...
http://rosettacode.org/wiki/Knapsack_problem/Unbounded
Knapsack problem/Unbounded
A traveler gets diverted and has to make an unscheduled stop in what turns out to be Shangri La.   Opting to leave, he is allowed to take as much as he likes of the following items, so long as it will fit in his knapsack, and he can carry it. He knows that he can carry no more than   25   'weights' in total;   and tha...
#Pascal
Pascal
Program Knapsack(output);   uses math;   type bounty = record value: longint; weight, volume: real; end;   const panacea: bounty = (value:3000; weight: 0.3; volume: 0.025); ichor: bounty = (value:1800; weight: 0.2; volume: 0.015); gold: bounty = (value:2500; weight: 2.0; volume: 0.002); sa...
http://rosettacode.org/wiki/Keyboard_input/Obtain_a_Y_or_N_response
Keyboard input/Obtain a Y or N response
Task Obtain a valid   Y   or   N   response from the keyboard. The keyboard should be flushed, so that any outstanding key-presses are removed, preventing any existing   Y   or   N   key-press from being evaluated. The response should be obtained as soon as   Y   or   N   are pressed, and there should be no need t...
#Scala
Scala
println(if (scala.io.StdIn.readBoolean) "Yes typed." else "Something else.")
http://rosettacode.org/wiki/Keyboard_input/Obtain_a_Y_or_N_response
Keyboard input/Obtain a Y or N response
Task Obtain a valid   Y   or   N   response from the keyboard. The keyboard should be flushed, so that any outstanding key-presses are removed, preventing any existing   Y   or   N   key-press from being evaluated. The response should be obtained as soon as   Y   or   N   are pressed, and there should be no need t...
#Seed7
Seed7
$ include "seed7_05.s7i"; include "keybd.s7i";   const func boolean: yesOrNo (in string: prompt) is func result var boolean: yes is FALSE; local var char: answer is ' '; begin while keypressed(KEYBOARD) do ignore(getc(KEYBOARD)); end while; write(prompt); repeat answer := low...
http://rosettacode.org/wiki/Knapsack_problem/Continuous
Knapsack problem/Continuous
A thief burgles a butcher's shop, where he can select from some items. The thief knows the weights and prices of each items.   Because he has a knapsack with 15 kg maximal capacity, he wants to select the items such that he would have his profit maximized.   He may cut the items;   the item has a reduced price after...
#PHP
PHP
/* Added by @1x24. Translated from C++. Uses the PHP 7.x spaceship operator */ $data = [ [ 'name'=>'beef', 'weight'=>3.8, 'cost'=>36, ], [ 'name'=>'pork', 'weight'=>5.4, 'cost'=>43, ], [ 'name'=>'ham', 'weight'=>3.6, 'cost'=>90, ], [ 'name'=>'greaves', 'w...
http://rosettacode.org/wiki/Knapsack_problem/Bounded
Knapsack problem/Bounded
A tourist wants to make a good trip at the weekend with his friends. They will go to the mountains to see the wonders of nature.   So he needs some items during the trip.   Food, clothing, etc.   He has a good knapsack for carrying the things, but he knows that he can carry only 4 kg weight in his knapsack, because th...
#REXX
REXX
/*REXX program solves a knapsack problem (22 items + repeats, with weight restriction.*/ call @gen /*generate items and initializations. */ call @sort /*sort items by decreasing their weight*/ call build ...
http://rosettacode.org/wiki/Jump_anywhere
Jump anywhere
Imperative programs conditional structures loops local jumps This task is to demonstrate a local jump and a global jump and the various other types of jumps that the language supports. For the purpose of this task, the jumps need not be used for a single purpose and you have the freedom to use these jumps for different...
#Harbour
Harbour
import Control.Monad.Cont   data LabelT r m = LabelT (ContT r m ())   label :: ContT r m (LabelT r m) label = callCC subprog where subprog lbl = let l = LabelT (lbl l) in return l   goto :: LabelT r m -> ContT r m b goto (LabelT l) = const undefined <$> l   runProgram :: Monad m => ContT r m r -> m r runProgram progr...
http://rosettacode.org/wiki/Jump_anywhere
Jump anywhere
Imperative programs conditional structures loops local jumps This task is to demonstrate a local jump and a global jump and the various other types of jumps that the language supports. For the purpose of this task, the jumps need not be used for a single purpose and you have the freedom to use these jumps for different...
#Haskell
Haskell
import Control.Monad.Cont   data LabelT r m = LabelT (ContT r m ())   label :: ContT r m (LabelT r m) label = callCC subprog where subprog lbl = let l = LabelT (lbl l) in return l   goto :: LabelT r m -> ContT r m b goto (LabelT l) = const undefined <$> l   runProgram :: Monad m => ContT r m r -> m r runProgram progr...
http://rosettacode.org/wiki/Knapsack_problem/0-1
Knapsack problem/0-1
A tourist wants to make a good trip at the weekend with his friends. They will go to the mountains to see the wonders of nature, so he needs to pack well for the trip. He has a good knapsack for carrying things, but knows that he can carry a maximum of only 4kg in it,   and it will have to last the whole day. He cre...
#Ceylon
Ceylon
  module knapsack "1.0.0" { }  
http://rosettacode.org/wiki/Kaprekar_numbers
Kaprekar numbers
A positive integer is a Kaprekar number if: It is   1     (unity) The decimal representation of its square may be split once into two parts consisting of positive integers which sum to the original number. Note that a split resulting in a part consisting purely of 0s is not valid, as 0 is not considered positive. ...
#CLU
CLU
% This program assumes a 64-bit system. % On a 32-bit system, the main task (show Kaprekar numbers < 10,000) % will run correctly, but the extra credit part will crash with % an overflow exception.   % Yield all positive splits of a number splits = iter (n, base: int) yields (int,int) step: int := base while n ...
http://rosettacode.org/wiki/Kaprekar_numbers
Kaprekar numbers
A positive integer is a Kaprekar number if: It is   1     (unity) The decimal representation of its square may be split once into two parts consisting of positive integers which sum to the original number. Note that a split resulting in a part consisting purely of 0s is not valid, as 0 is not considered positive. ...
#CoffeeScript
CoffeeScript
splitAt = (str, idx) -> ans = [ str.substring(0, idx), str.substring(idx) ] if ans[0] == "" ans[0] = "0" ans   getKaprekarParts = (longValue, sqrStr, base) -> for j in [ 0 .. sqrStr.length / 2 ] parts = splitAt(sqrStr, j) nums = (parseInt(n, base) for n in parts)   # if t...
http://rosettacode.org/wiki/JSON
JSON
Load a JSON string into a data structure. Also, create a new data structure and serialize it into JSON. Use objects and arrays (as appropriate for your language) and make sure your JSON is valid (https://jsonformatter.org).
#D
D
import std.stdio, std.json;   void main() { auto j = parseJSON(`{ "foo": 1, "bar": [10, "apples"] }`); writeln(toJSON(&j)); }
http://rosettacode.org/wiki/JSON
JSON
Load a JSON string into a data structure. Also, create a new data structure and serialize it into JSON. Use objects and arrays (as appropriate for your language) and make sure your JSON is valid (https://jsonformatter.org).
#Dart
Dart
import 'dart:convert' show jsonDecode, jsonEncode;   main(){ var json_string = ''' { "rosetta_code": { "task": "json", "language": "dart", "descriptions": [ "fun!", "easy to learn!", "awesome!" ] } } ''';   // decode string into Map<String, dynamic> var json_object = jsonDecode(json_string);   for (...
http://rosettacode.org/wiki/Joystick_position
Joystick position
The task is to determine the joystick position and represent this on the display via a crosshair. For a centred joystick, the crosshair should appear in the centre of the screen. If the joystick is pushed left or right, then the cross hair should move left or right according to the extent that the joystick is pushed. ...
#PicoLisp
PicoLisp
(load "@lib/openGl.l")   (setq *JoyX 0.0 *JoyY 0.0)   (glutInit) (glutInitDisplayMode (| GLUT_RGBA GLUT_DOUBLE GLUT_ALPHA GLUT_DEPTH)) (glutInitWindowSize 400 400) (glutCreateWindow "Joystick")   (glClearColor 0.3 0.3 0.5 0)   (displayPrg (glClear GL_COLOR_BUFFER_BIT) (glBegin GL_LINES) (glVertex2f *JoyX (- *...
http://rosettacode.org/wiki/Joystick_position
Joystick position
The task is to determine the joystick position and represent this on the display via a crosshair. For a centred joystick, the crosshair should appear in the centre of the screen. If the joystick is pushed left or right, then the cross hair should move left or right according to the extent that the joystick is pushed. ...
#PureBasic
PureBasic
If InitJoystick() = 0 MessageRequester("Error!", "Need to connect a joystick", #PB_MessageRequester_Ok) End EndIf   ;some constants for Window positioning #WindowW = 100: #WindowH = 100 #CrossW = 10 #p1 = (#WindowW - #CrossW) / 2 #p2 = (#WindowW / 2 - #CrossW)   If OpenWindow(0, 0, 0, #WindowW * 2 + 10, #WindowH, "...
http://rosettacode.org/wiki/K-d_tree
K-d tree
This page uses content from Wikipedia. The original article was at K-d tree. The list of authors can be seen in the page history. As with Rosetta Code, the text of Wikipedia is available under the GNU FDL. (See links for details on variance) A k-d tree (short for k-dimensional tree) is a space-partitioning data str...
#Wren
Wren
import "/dynamic" for Tuple import "/math" for Nums import "/seq" for Lst import "/sort" for Sort import "random" for Random   // A Point is represented by a 2 element List of Nums var PtSqd = Fn.new { |p, q| Nums.sum(Lst.zip(p, q).map { |r| (r[0] - r[1]) * (r[0] - r[1]) }) }   var HyperRect = Tuple.create("HyperRect",...
http://rosettacode.org/wiki/Knight%27s_tour
Knight's tour
Task Problem: you have a standard 8x8 chessboard, empty but for a single knight on some square. Your task is to emit a series of legal knight moves that result in the knight visiting every square on the chessboard exactly once. Note that it is not a requirement that the tour be "closed"; that is, the knight need not e...
#EchoLisp
EchoLisp
  (require 'plot) (define *knight-moves* '((2 . 1)(2 . -1 ) (1 . -2) (-1 . -2 )(-2 . -1) (-2 . 1) (-1 . 2) (1 . 2))) (define *hit-squares* null) (define *legal-moves* null) (define *tries* 0)   (define (square x y n ) (+ y (* x n))) (define (dim n) (1- (* n n))) ; n^2 - 1   ;; check legal knight move from sq ;; ret...
http://rosettacode.org/wiki/Knuth_shuffle
Knuth shuffle
The   Knuth shuffle   (a.k.a. the Fisher-Yates shuffle)   is an algorithm for randomly shuffling the elements of an array. Task Implement the Knuth shuffle for an integer array (or, if possible, an array of any type). Specification Given an array items with indices ranging from 0 to last, the algorithm can be d...
#E
E
def shuffle(array, random) { for bound in (2..(array.size())).descending() { def i := random.nextInt(bound) def swapTo := bound - 1 def t := array[swapTo] array[swapTo] := array[i] array[i] := t } }
http://rosettacode.org/wiki/K-means%2B%2B_clustering
K-means++ clustering
K-means++ clustering K-means This data was partitioned into 7 clusters using the K-means algorithm. The task is to implement the K-means++ algorithm. Produce a function which takes two arguments: the number of clusters K, and the dataset to classify. K is a positive integer and the dataset is a list of points in the C...
#Mathematica.2FWolfram_Language
Mathematica/Wolfram Language
initM[list_List, k_Integer, distFunc_Symbol] := Module[{m = {RandomChoice[list]}, n, d}, While[Length[m] < k, n = RandomChoice@Nearest[m, #] & /@ list; d = Apply[distFunc, Transpose[{n, list}], {1}]; m = Append[m, RandomChoice[d -> list]] ]; m ]; kmeanspp[list_, k_, opts : OptionsPatter...
http://rosettacode.org/wiki/Kernighans_large_earthquake_problem
Kernighans large earthquake problem
Brian Kernighan, in a lecture at the University of Nottingham, described a problem on which this task is based. Problem You are given a a data file of thousands of lines; each of three `whitespace` separated fields: a date, a one word name and the magnitude of the event. Example lines from the file would be lines li...
#Snobol
Snobol
input(.quake, 1,, 'data.txt')  :f(err) num = '.0123456789'   line test = quake  :f(end) test span(num) . magnitude rpos(0)  :f(line) output = gt(magnitude,6) test  :(line)   err output = 'Error!' end
http://rosettacode.org/wiki/Kernighans_large_earthquake_problem
Kernighans large earthquake problem
Brian Kernighan, in a lecture at the University of Nottingham, described a problem on which this task is based. Problem You are given a a data file of thousands of lines; each of three `whitespace` separated fields: a date, a one word name and the magnitude of the event. Example lines from the file would be lines li...
#Swift
Swift
import Foundation   guard let path = Array(CommandLine.arguments.dropFirst()).first else { fatalError() }   let fileData = FileManager.default.contents(atPath: path)! let eventData = String(data: fileData, encoding: .utf8)!   for line in eventData.components(separatedBy: "\n") { guard let lastSpace = line.lastIndex...
http://rosettacode.org/wiki/Kernighans_large_earthquake_problem
Kernighans large earthquake problem
Brian Kernighan, in a lecture at the University of Nottingham, described a problem on which this task is based. Problem You are given a a data file of thousands of lines; each of three `whitespace` separated fields: a date, a one word name and the magnitude of the event. Example lines from the file would be lines li...
#Tcl
Tcl
catch {console show} ;## show console when running from tclwish catch {wm withdraw .}   set filename "data.txt" set fh [open $filename] set NR 0 ;# number-of-record, means linenumber   while {[gets $fh line]>=0} { ;# gets returns length of line, -1 means eof incr NR set line2 [re...
http://rosettacode.org/wiki/Julia_set
Julia set
Task Generate and draw a Julia set. Related tasks   Mandelbrot Set
#F.C5.8Drmul.C3.A6
Fōrmulæ
package main   import ( "image" "image/color" "image/png" "log" "os" "sync" )   func main() { const ( width, height = 800.0, 600.0 maxIter = 255 cX, cY = -0.7, 0.27015 fileName = "julia.png" ) img := image.NewNRGBA(image.Rect(0, 0, width, height))   var wg sync.WaitGroup wg.Add(widt...
http://rosettacode.org/wiki/Knapsack_problem/Unbounded
Knapsack problem/Unbounded
A traveler gets diverted and has to make an unscheduled stop in what turns out to be Shangri La.   Opting to leave, he is allowed to take as much as he likes of the following items, so long as it will fit in his knapsack, and he can carry it. He knows that he can carry no more than   25   'weights' in total;   and tha...
#Perl
Perl
my (@names, @val, @weight, @vol, $max_vol, $max_weight, $vsc, $wsc);   if (1) { # change 1 to 0 for different data set @names = qw(panacea icor gold); @val = qw(3000 1800 2500); @weight = qw(3 2 20 ); @vol = qw(25 15 2 ); $max_...
http://rosettacode.org/wiki/Keyboard_input/Obtain_a_Y_or_N_response
Keyboard input/Obtain a Y or N response
Task Obtain a valid   Y   or   N   response from the keyboard. The keyboard should be flushed, so that any outstanding key-presses are removed, preventing any existing   Y   or   N   key-press from being evaluated. The response should be obtained as soon as   Y   or   N   are pressed, and there should be no need t...
#Sidef
Sidef
func prompt_yn { static rk = frequire('Term::ReadKey'); rk.ReadMode(4); # change to raw input mode   var key = ''; while (key !~ /[yn]/i) { while (rk.ReadKey(-1) != nil) {}; # discard any previous input print "Type Y/N: "; say (key = rk.ReadKey(0)); # read a single...
http://rosettacode.org/wiki/Keyboard_input/Obtain_a_Y_or_N_response
Keyboard input/Obtain a Y or N response
Task Obtain a valid   Y   or   N   response from the keyboard. The keyboard should be flushed, so that any outstanding key-presses are removed, preventing any existing   Y   or   N   key-press from being evaluated. The response should be obtained as soon as   Y   or   N   are pressed, and there should be no need t...
#Tcl
Tcl
proc yesno {{message "Press Y or N to continue"}} { fconfigure stdin -blocking 0 exec stty raw read stdin ; # flush puts -nonewline "${message}: " flush stdout while {![eof stdin]} { set c [string tolower [read stdin 1]] if {$c eq "y" || $c eq "n"} break } puts [string to...
http://rosettacode.org/wiki/Knapsack_problem/Continuous
Knapsack problem/Continuous
A thief burgles a butcher's shop, where he can select from some items. The thief knows the weights and prices of each items.   Because he has a knapsack with 15 kg maximal capacity, he wants to select the items such that he would have his profit maximized.   He may cut the items;   the item has a reduced price after...
#Picat
Picat
go => items(Items), weights(Weights), values(Values), knapsack_max_weight(MaxWeight),   knapsack(Weights,Values,MaxWeight, X,TotalWeight,TotalValue), nl,   printf("Total weight: %0.2f Total value: %0.2f\n", TotalWeight,TotalValue), foreach(I in 1..Items.len) if X[I] > 0.0 then printf("%-8w: ...
http://rosettacode.org/wiki/Knapsack_problem/Bounded
Knapsack problem/Bounded
A tourist wants to make a good trip at the weekend with his friends. They will go to the mountains to see the wonders of nature.   So he needs some items during the trip.   Food, clothing, etc.   He has a good knapsack for carrying the things, but he knows that he can carry only 4 kg weight in his knapsack, because th...
#Ruby
Ruby
  # Item struct to represent each item in the problem Struct.new('Item', :name, :weight, :value, :count)   $items = [ Struct::Item.new('map', 9, 150, 1), Struct::Item.new('compass', 13, 35, 1), Struct::Item.new('water', 153, 200, 3), Struct::Item.new('sandwich', 50, 60, 2), Struct::Item.new('glucose', 15, 60,...
http://rosettacode.org/wiki/Jump_anywhere
Jump anywhere
Imperative programs conditional structures loops local jumps This task is to demonstrate a local jump and a global jump and the various other types of jumps that the language supports. For the purpose of this task, the jumps need not be used for a single purpose and you have the freedom to use these jumps for different...
#i
i
//'i' does not have goto statements, instead control flow is the only legal way to navigate the program. concept there() { print("Hello there") return //The return statement goes back to where the function was called. print("Not here") }   software { loop { break //This breaks the loop, the code after the loop bl...
http://rosettacode.org/wiki/Jump_anywhere
Jump anywhere
Imperative programs conditional structures loops local jumps This task is to demonstrate a local jump and a global jump and the various other types of jumps that the language supports. For the purpose of this task, the jumps need not be used for a single purpose and you have the freedom to use these jumps for different...
#J
J
F=: verb define smoutput 'Now we are in F' G'' smoutput 'Now we are back in F' )   G=: verb define smoutput 'Now we are in G' throw. )   F'' Now we are in F Now we are in G
http://rosettacode.org/wiki/Knapsack_problem/0-1
Knapsack problem/0-1
A tourist wants to make a good trip at the weekend with his friends. They will go to the mountains to see the wonders of nature, so he needs to pack well for the trip. He has a good knapsack for carrying things, but knows that he can carry a maximum of only 4kg in it,   and it will have to last the whole day. He cre...
#Clojure
Clojure
(def item-data [ "map" 9 150 "compass" 13 35 "water" 153 200 "sandwich" 50 160 "glucose" 15 60 "tin" 68 45 "banana" 27 60 "apple" 39 40 "cheese" 23 30 "beer" 52 10 "suntan cream" 11 70 "camera" 32 30 "t-shirt"...
http://rosettacode.org/wiki/Kaprekar_numbers
Kaprekar numbers
A positive integer is a Kaprekar number if: It is   1     (unity) The decimal representation of its square may be split once into two parts consisting of positive integers which sum to the original number. Note that a split resulting in a part consisting purely of 0s is not valid, as 0 is not considered positive. ...
#Common_Lisp
Common Lisp
;; make an infinite list whose accumulated sums give all ;; numbers n where n mod (base - 1) == n^2 mod (base - 1) (defun res-list (base) (let* ((b (- base 1)) (l (remove-if-not (lambda (x) (= (rem x b) (rem (* x x) b))) (loop for x from 0 below b collect x))) (ret (append l (list b))) ...
http://rosettacode.org/wiki/JSON
JSON
Load a JSON string into a data structure. Also, create a new data structure and serialize it into JSON. Use objects and arrays (as appropriate for your language) and make sure your JSON is valid (https://jsonformatter.org).
#Delphi
Delphi
  program JsonTest;   {$APPTYPE CONSOLE}   {$R *.res}   uses System.SysUtils, Json;   type TJsonObjectHelper = class helper for TJsonObject public class function Deserialize(data: string): TJsonObject; static; function Serialize: string; end;   { TJsonObjectHelper }   class function TJsonObjectHelper....
http://rosettacode.org/wiki/Joystick_position
Joystick position
The task is to determine the joystick position and represent this on the display via a crosshair. For a centred joystick, the crosshair should appear in the centre of the screen. If the joystick is pushed left or right, then the cross hair should move left or right according to the extent that the joystick is pushed. ...
#Python
Python
import sys import pygame   pygame.init()   # Create a clock (for framerating) clk = pygame.time.Clock()   # Grab joystick 0 if pygame.joystick.get_count() == 0: raise IOError("No joystick detected") joy = pygame.joystick.Joystick(0) joy.init()   # Create display size = width, height = 600, 600 screen = pygame.displ...
http://rosettacode.org/wiki/K-d_tree
K-d tree
This page uses content from Wikipedia. The original article was at K-d tree. The list of authors can be seen in the page history. As with Rosetta Code, the text of Wikipedia is available under the GNU FDL. (See links for details on variance) A k-d tree (short for k-dimensional tree) is a space-partitioning data str...
#zkl
zkl
class KdTree{ const NEAREST=0, DIST_SQD=1, NODES_VISITED=2; class KdNode{ fcn init(_dom_elt,_split,_left,_right){ var dom_elt=_dom_elt.apply("toFloat"), split=_split, left=_left, right=_right; } } fcn init(pts,_bounds){ // pts is points is ( (x,y,..),..) var n=fcn(split, exset){ ...
http://rosettacode.org/wiki/Knight%27s_tour
Knight's tour
Task Problem: you have a standard 8x8 chessboard, empty but for a single knight on some square. Your task is to emit a series of legal knight moves that result in the knight visiting every square on the chessboard exactly once. Note that it is not a requirement that the tour be "closed"; that is, the knight need not e...
#Elixir
Elixir
defmodule Board do import Integer, only: [is_odd: 1]   defmodule Cell do defstruct [:value, :adj] end   @adjacent [[-1,-2],[-2,-1],[-2,1],[-1,2],[1,2],[2,1],[2,-1],[1,-2]]   defp initialize(rows, cols) do board = for i <- 1..rows, j <- 1..cols, into: %{}, do: {{i,j}, true} for i <- 1..rows, j <- ...
http://rosettacode.org/wiki/Knuth_shuffle
Knuth shuffle
The   Knuth shuffle   (a.k.a. the Fisher-Yates shuffle)   is an algorithm for randomly shuffling the elements of an array. Task Implement the Knuth shuffle for an integer array (or, if possible, an array of any type). Specification Given an array items with indices ranging from 0 to last, the algorithm can be d...
#EasyLang
EasyLang
func shuffle . a[] . for i = len a[] downto 2 r = random i swap a[r] a[i - 1] . . arr[] = [ 1 2 3 ] call shuffle arr[] print arr[]  
http://rosettacode.org/wiki/K-means%2B%2B_clustering
K-means++ clustering
K-means++ clustering K-means This data was partitioned into 7 clusters using the K-means algorithm. The task is to implement the K-means++ algorithm. Produce a function which takes two arguments: the number of clusters K, and the dataset to classify. K is a positive integer and the dataset is a list of points in the C...
#Nim
Nim
# # compile: # nim c -d:release kmeans.nim # # and pipe the resultant EPS output to a file, e.g. # # kmeans > results.eps # import random, math, strutils   const FloatMax = 1.0e100 nPoints = 100_000 nClusters = 11   type Point = object x, y: float group: int Points = seq[Point] ClusterDist =...
http://rosettacode.org/wiki/Kernighans_large_earthquake_problem
Kernighans large earthquake problem
Brian Kernighan, in a lecture at the University of Nottingham, described a problem on which this task is based. Problem You are given a a data file of thousands of lines; each of three `whitespace` separated fields: a date, a one word name and the magnitude of the event. Example lines from the file would be lines li...
#Visual_Basic_.NET
Visual Basic .NET
Imports System.IO   Module Module1   Function LargeEarthquakes(filename As String, limit As Double) As IEnumerable(Of String()) Return From line In File.ReadLines(filename) Let parts = line.Split(CType(Nothing, Char()), StringSplitOptions.RemoveEmptyEntries) Where Double.Parse(...
http://rosettacode.org/wiki/Kernighans_large_earthquake_problem
Kernighans large earthquake problem
Brian Kernighan, in a lecture at the University of Nottingham, described a problem on which this task is based. Problem You are given a a data file of thousands of lines; each of three `whitespace` separated fields: a date, a one word name and the magnitude of the event. Example lines from the file would be lines li...
#Vlang
Vlang
import os fn main() { lines := os.read_lines('data.txt')? println('Those earthquakes with a magnitude > 6.0 are:\n') for line in lines { fields := line.fields() mag := fields[2].f64() if mag > 6.0 { println(line) } } }
http://rosettacode.org/wiki/Kernighans_large_earthquake_problem
Kernighans large earthquake problem
Brian Kernighan, in a lecture at the University of Nottingham, described a problem on which this task is based. Problem You are given a a data file of thousands of lines; each of three `whitespace` separated fields: a date, a one word name and the magnitude of the event. Example lines from the file would be lines li...
#Wren
Wren
import "io" for File import "os" for Process import "/pattern" for Pattern   var args = Process.arguments if (args.count != 1) Fiber.abort("Please pass just the name of the date file.") var fileName = args[0] var lines = File.read(fileName).split("\n").map { |l| l.trim() }.where { |l| l != "" } var p = Pattern.new("+1/...
http://rosettacode.org/wiki/Julia_set
Julia set
Task Generate and draw a Julia set. Related tasks   Mandelbrot Set
#Go
Go
package main   import ( "image" "image/color" "image/png" "log" "os" "sync" )   func main() { const ( width, height = 800.0, 600.0 maxIter = 255 cX, cY = -0.7, 0.27015 fileName = "julia.png" ) img := image.NewNRGBA(image.Rect(0, 0, width, height))   var wg sync.WaitGroup wg.Add(widt...
http://rosettacode.org/wiki/Knapsack_problem/Unbounded
Knapsack problem/Unbounded
A traveler gets diverted and has to make an unscheduled stop in what turns out to be Shangri La.   Opting to leave, he is allowed to take as much as he likes of the following items, so long as it will fit in his knapsack, and he can carry it. He knows that he can carry no more than   25   'weights' in total;   and tha...
#Phix
Phix
-- demo\rosetta\knapsack.exw with javascript_semantics function knapsack(sequence res, goodies, atom profit, weight, volume, at=1, sequence chosen={}) atom {?,pitem,witem,vitem} = goodies[at] integer n = min(floor(weight/witem),floor(volume/vitem)) chosen &= n profit += n*pitem -- increase profit ...
http://rosettacode.org/wiki/Keyboard_input/Obtain_a_Y_or_N_response
Keyboard input/Obtain a Y or N response
Task Obtain a valid   Y   or   N   response from the keyboard. The keyboard should be flushed, so that any outstanding key-presses are removed, preventing any existing   Y   or   N   key-press from being evaluated. The response should be obtained as soon as   Y   or   N   are pressed, and there should be no need t...
#TXR
TXR
(with-resources ((tio-orig (tcgetattr) (tcsetattr tio-orig))) (let ((tio (copy tio-orig))) tio.(go-raw) (tcsetattr tio tcsaflush) ;; third arg optional, defaults to tcsadrain (whilet ((k (get-char)) ((not (member k '(#\y #\n #\Y #\N))))))))
http://rosettacode.org/wiki/Keyboard_input/Obtain_a_Y_or_N_response
Keyboard input/Obtain a Y or N response
Task Obtain a valid   Y   or   N   response from the keyboard. The keyboard should be flushed, so that any outstanding key-presses are removed, preventing any existing   Y   or   N   key-press from being evaluated. The response should be obtained as soon as   Y   or   N   are pressed, and there should be no need t...
#UNIX_Shell
UNIX Shell
getkey() { local stty="$(stty -g)" trap "stty $stty; trap SIGINT; return 128" SIGINT stty cbreak -echo local key while true; do key=$(dd count=1 2>/dev/null) || return $? if [ -z "$1" ] || [[ "$key" == [$1] ]]; then break fi done stty $stty echo "$key" return 0 }   yorn() { echo -...
http://rosettacode.org/wiki/Knapsack_problem/Continuous
Knapsack problem/Continuous
A thief burgles a butcher's shop, where he can select from some items. The thief knows the weights and prices of each items.   Because he has a knapsack with 15 kg maximal capacity, he wants to select the items such that he would have his profit maximized.   He may cut the items;   the item has a reduced price after...
#PicoLisp
PicoLisp
(scl 2)   (de *Items ("beef" 3.8 36.0) ("pork" 5.4 43.0) ("ham" 3.6 90.0) ("greaves" 2.4 45.0) ("flitch" 4.0 30.0) ("brawn" 2.5 56.0) ("welt" 3.7 67.0) ("salami" 3.0 95.0) ("sausage" 5.9 98.0) )   (let K (make (let Weight 0 (for I (by '((L) (*/ (caddr L) -1.0 (cadr L))) sort...
http://rosettacode.org/wiki/Knapsack_problem/Bounded
Knapsack problem/Bounded
A tourist wants to make a good trip at the weekend with his friends. They will go to the mountains to see the wonders of nature.   So he needs some items during the trip.   Food, clothing, etc.   He has a good knapsack for carrying the things, but he knows that he can carry only 4 kg weight in his knapsack, because th...
#SAS
SAS
/* create SAS data set */ data mydata; input item $1-23 weight value pieces; datalines; map 9 150 1 compass 13 35 1 water 153 200 2 sandwich 50 60 2 glucose 15 60 2 tin 68 45 3 bana...
http://rosettacode.org/wiki/Jump_anywhere
Jump anywhere
Imperative programs conditional structures loops local jumps This task is to demonstrate a local jump and a global jump and the various other types of jumps that the language supports. For the purpose of this task, the jumps need not be used for a single purpose and you have the freedom to use these jumps for different...
#Java
Java
loop1: while (x != 0) { loop2: for (int i = 0; i < 10; i++) { loop3: do { //some calculations... if (/*some condition*/) { //this continue will skip the rest of the while loop code and start it over at the next iteration continue loop1; } ...
http://rosettacode.org/wiki/Knapsack_problem/0-1
Knapsack problem/0-1
A tourist wants to make a good trip at the weekend with his friends. They will go to the mountains to see the wonders of nature, so he needs to pack well for the trip. He has a good knapsack for carrying things, but knows that he can carry a maximum of only 4kg in it,   and it will have to last the whole day. He cre...
#Common_Lisp
Common Lisp
;;; memoize (defmacro mm-set (p v) `(if ,p ,p (setf ,p ,v)))   (defun knapsack (max-weight items) (let ((cache (make-array (list (1+ max-weight) (1+ (length items))) :initial-element nil)))   (labels ((knapsack1 (spc items) (if (not items) (return-from knapsack1 (list 0 0 '()))) (mm-set (aref cache spc (l...
http://rosettacode.org/wiki/Kaprekar_numbers
Kaprekar numbers
A positive integer is a Kaprekar number if: It is   1     (unity) The decimal representation of its square may be split once into two parts consisting of positive integers which sum to the original number. Note that a split resulting in a part consisting purely of 0s is not valid, as 0 is not considered positive. ...
#D
D
import std.stdio, std.conv, std.algorithm, std.range;   bool isKaprekar(in long n) pure /*nothrow*/ @safe in { assert(n > 0, "isKaprekar(n) is defined for n > 0."); } body { if (n == 1) return true; immutable sn = text(n ^^ 2);   foreach (immutable i; 1 .. sn.length) { immutable a = sn[0...
http://rosettacode.org/wiki/JSON
JSON
Load a JSON string into a data structure. Also, create a new data structure and serialize it into JSON. Use objects and arrays (as appropriate for your language) and make sure your JSON is valid (https://jsonformatter.org).
#EchoLisp
EchoLisp
  ;; JSON standard types : strings, numbers, and arrays (vectors) (export-json #(6 7 8 9)) → "[6,7,8,9]" (export-json #("alpha" "beta" "gamma")) → "["alpha","beta","gamma"]"   (json-import "[6,7,8,9]") → #( 6 7 8 9) (json-import #<< ["alpha","beta","gamma"] >>#) → #( "alpha" "beta" "gamma")   ;; EchoLisp ty...
http://rosettacode.org/wiki/Joystick_position
Joystick position
The task is to determine the joystick position and represent this on the display via a crosshair. For a centred joystick, the crosshair should appear in the centre of the screen. If the joystick is pushed left or right, then the cross hair should move left or right according to the extent that the joystick is pushed. ...
#Raku
Raku
use experimental :pack;   # Joysticks generally show up in the /dev/input/ directory as js(n) where n is # the number assigned by the OS. E.G. /dev/input/js1 . In my particular case:   my $device = '/dev/input/js0';   my $exit = 0;   my $event-stream = $device.IO.open(:bin); my $js = $event-stream.Supply(:8size);   my ...
http://rosettacode.org/wiki/Knight%27s_tour
Knight's tour
Task Problem: you have a standard 8x8 chessboard, empty but for a single knight on some square. Your task is to emit a series of legal knight moves that result in the knight visiting every square on the chessboard exactly once. Note that it is not a requirement that the tour be "closed"; that is, the knight need not e...
#Elm
Elm
module Main exposing (main)   import Browser exposing (element) import Html as H import Html.Attributes as HA import List exposing (filter, head, length, map, map2, member, tail) import List.Extra exposing (andThen, minimumBy) import String exposing (join) import Svg exposing (g, line, rect, svg) import Svg.Attributes ...
http://rosettacode.org/wiki/Knuth_shuffle
Knuth shuffle
The   Knuth shuffle   (a.k.a. the Fisher-Yates shuffle)   is an algorithm for randomly shuffling the elements of an array. Task Implement the Knuth shuffle for an integer array (or, if possible, an array of any type). Specification Given an array items with indices ranging from 0 to last, the algorithm can be d...
#EchoLisp
EchoLisp
  Remark- The native '''shuffle''' function implementation in EchoLisp has been replaced by this one. Thx Rosetta Code. (lib 'list) ;; for list-permute   ;; use "inside-out" algorithm, no swapping needed. ;; returns a random permutation vector of [0 .. n-1] (define (rpv n (j)) (define v (make-vector n)) (for [(i n)]...
http://rosettacode.org/wiki/K-means%2B%2B_clustering
K-means++ clustering
K-means++ clustering K-means This data was partitioned into 7 clusters using the K-means algorithm. The task is to implement the K-means++ algorithm. Produce a function which takes two arguments: the number of clusters K, and the dataset to classify. K is a positive integer and the dataset is a list of points in the C...
#Phix
Phix
-- demo\rosetta\K_means_clustering.exw -- Press F5 to restart include pGUI.e   Ihandle dlg, canvas, timer cdCanvas cddbuffer, cdcanvas   constant TITLE = "K-means++ clustering"   constant useGoInitialData = false -- (not very well centered)   constant N = 30000, -- number of points K...
http://rosettacode.org/wiki/Kernighans_large_earthquake_problem
Kernighans large earthquake problem
Brian Kernighan, in a lecture at the University of Nottingham, described a problem on which this task is based. Problem You are given a a data file of thousands of lines; each of three `whitespace` separated fields: a date, a one word name and the magnitude of the event. Example lines from the file would be lines li...
#XPL0
XPL0
int C; [loop [OpenO(8); \get line from input file repeat C:= ChIn(1); ChOut(8, C); \save it in buffer device 8 if C = $1A\EOF\ then quit; until C = $0A\LF\; OpenI(8); repeat until ChIn(8) <= $20\space\; repeat until ChIn(8) > ...
http://rosettacode.org/wiki/Kernighans_large_earthquake_problem
Kernighans large earthquake problem
Brian Kernighan, in a lecture at the University of Nottingham, described a problem on which this task is based. Problem You are given a a data file of thousands of lines; each of three `whitespace` separated fields: a date, a one word name and the magnitude of the event. Example lines from the file would be lines li...
#Yabasic
Yabasic
if peek("argument") then filename$ = peek$("argument") else filename$ = "data.txt" end if   dim tok$(1) a = open(filename$) if not a error "Could not open '" + filename$ + "' for reading" while(not eof(a)) line input #a a$ void = token(a$, tok$()) if val(tok$(3)) > 6 print a$ wend close a
http://rosettacode.org/wiki/Kernighans_large_earthquake_problem
Kernighans large earthquake problem
Brian Kernighan, in a lecture at the University of Nottingham, described a problem on which this task is based. Problem You are given a a data file of thousands of lines; each of three `whitespace` separated fields: a date, a one word name and the magnitude of the event. Example lines from the file would be lines li...
#zkl
zkl
fcn equake(data,out=Console){ data.pump(out,fcn(line){ 6.0line.split()[-1] },Void.Filter) }
http://rosettacode.org/wiki/Julia_set
Julia set
Task Generate and draw a Julia set. Related tasks   Mandelbrot Set
#Haskell
Haskell
import System.Environment (getArgs)   plotChar :: Int -> Float -> Float -> Float -> Float -> Char plotChar iter cReal cImag y x | zReal^2 > 10000 = ' ' | iter == 1 = '#' | otherwise = plotChar (pred iter) cReal cImag zImag zReal where zReal = x * x - y * y + cReal zImag = x * y * 2 + cImag   par...
http://rosettacode.org/wiki/Knapsack_problem/Unbounded
Knapsack problem/Unbounded
A traveler gets diverted and has to make an unscheduled stop in what turns out to be Shangri La.   Opting to leave, he is allowed to take as much as he likes of the following items, so long as it will fit in his knapsack, and he can carry it. He knows that he can carry no more than   25   'weights' in total;   and tha...
#Picat
Picat
import mip.   go => data(Items,Value,Weight,Volume,MaxWeight,MaxVolume), knapsack_problem(Value,Weight,Volume,MaxWeight,MaxVolume, X,Z),   println(z=Z), println(x=X), N = Items.len,   foreach({Item,Num} in zip(Items,X), Num > 0) printf("Take %d of %w\n", Num,Item) end,   print("\nTotal volume: "), ...
http://rosettacode.org/wiki/Knapsack_problem/Unbounded
Knapsack problem/Unbounded
A traveler gets diverted and has to make an unscheduled stop in what turns out to be Shangri La.   Opting to leave, he is allowed to take as much as he likes of the following items, so long as it will fit in his knapsack, and he can carry it. He knows that he can carry no more than   25   'weights' in total;   and tha...
#PicoLisp
PicoLisp
(de *Items ("panacea" 3 25 3000) ("ichor" 2 15 1800) ("gold" 20 2 2500) )   (de knapsack (Lst W V) (when Lst (let X (knapsack (cdr Lst) W V) (if (and (ge0 (dec 'W (cadar Lst))) (ge0 (dec 'V (caddar Lst)))) (maxi '((L) (sum cadddr L)) (li...
http://rosettacode.org/wiki/Keyboard_input/Obtain_a_Y_or_N_response
Keyboard input/Obtain a Y or N response
Task Obtain a valid   Y   or   N   response from the keyboard. The keyboard should be flushed, so that any outstanding key-presses are removed, preventing any existing   Y   or   N   key-press from being evaluated. The response should be obtained as soon as   Y   or   N   are pressed, and there should be no need t...
#VB-DOS
VB-DOS
OPTION EXPLICIT DIM T AS INTEGER T = MSGBOX("Click on yes or no", 4, "Option") PRINT "The response is "; IF T = 6 THEN PRINT "yes"; ELSE PRINT "no"; PRINT "." END
http://rosettacode.org/wiki/Keyboard_input/Obtain_a_Y_or_N_response
Keyboard input/Obtain a Y or N response
Task Obtain a valid   Y   or   N   response from the keyboard. The keyboard should be flushed, so that any outstanding key-presses are removed, preventing any existing   Y   or   N   key-press from being evaluated. The response should be obtained as soon as   Y   or   N   are pressed, and there should be no need t...
#Vedit_macro_language
Vedit macro language
Key_Purge() // flush keyboard buffer do { #1 = Get_Key("Are you sure? (Y/N): ") // prompt for a key #1 &= 0xdf // to upper case } while (#1 != 'Y' && #1 != 'N')
http://rosettacode.org/wiki/Knapsack_problem/Continuous
Knapsack problem/Continuous
A thief burgles a butcher's shop, where he can select from some items. The thief knows the weights and prices of each items.   Because he has a knapsack with 15 kg maximal capacity, he wants to select the items such that he would have his profit maximized.   He may cut the items;   the item has a reduced price after...
#PL.2FI
PL/I
*process source xref attributes; KNAPSACK_CONTINUOUS: Proc Options(main); /*-------------------------------------------------------------------- * 19.09.2014 Walter Pachl translated from FORTRAN *-------------------------------------------------------------------*/ Dcl (divide,float,hbound,repeat) Builtin; Dcl ...
http://rosettacode.org/wiki/Knapsack_problem/Bounded
Knapsack problem/Bounded
A tourist wants to make a good trip at the weekend with his friends. They will go to the mountains to see the wonders of nature.   So he needs some items during the trip.   Food, clothing, etc.   He has a good knapsack for carrying the things, but he knows that he can carry only 4 kg weight in his knapsack, because th...
#Sidef
Sidef
var raw = <<'TABLE' map 9 150 1 compass 13 35 1 water 153 200 2 sandwich 50 60 2 glucose 15 60 2 tin 68 45 3 banana 27 60 3 apple 39 40 3 cheese 23 30 1 beer 52 ...
http://rosettacode.org/wiki/Jump_anywhere
Jump anywhere
Imperative programs conditional structures loops local jumps This task is to demonstrate a local jump and a global jump and the various other types of jumps that the language supports. For the purpose of this task, the jumps need not be used for a single purpose and you have the freedom to use these jumps for different...
#jq
jq
label $out | ... break $out ...
http://rosettacode.org/wiki/Jump_anywhere
Jump anywhere
Imperative programs conditional structures loops local jumps This task is to demonstrate a local jump and a global jump and the various other types of jumps that the language supports. For the purpose of this task, the jumps need not be used for a single purpose and you have the freedom to use these jumps for different...
#Julia
Julia
  function example() println("Hello ") @goto world println("Never printed") @label world println("world") end  
http://rosettacode.org/wiki/Knapsack_problem/0-1
Knapsack problem/0-1
A tourist wants to make a good trip at the weekend with his friends. They will go to the mountains to see the wonders of nature, so he needs to pack well for the trip. He has a good knapsack for carrying things, but knows that he can carry a maximum of only 4kg in it,   and it will have to last the whole day. He cre...
#Crystal
Crystal
require "bit_array"   struct BitArray def clone BitArray.new(size).tap { |new| new.to_slice.copy_from (to_slice) } end end   record Item, name : String, weight : Int32, value : Int32   record Selection, mask : BitArray, cur_index : Int32, total_value : Int32   class Knapsack @threshold_value = 0 @threshold_...
http://rosettacode.org/wiki/Kaprekar_numbers
Kaprekar numbers
A positive integer is a Kaprekar number if: It is   1     (unity) The decimal representation of its square may be split once into two parts consisting of positive integers which sum to the original number. Note that a split resulting in a part consisting purely of 0s is not valid, as 0 is not considered positive. ...
#Dart
Dart
  import 'dart:math'; void main() {   int x1; for(x1=1;x1<1000000;x1++){ int x; int i,y,y1,l1,z,l; double o,o1,o2,o3; x=pow(x1,2); for(i=0;;i++) {z=pow(10,i); if(x%z==x)break;} if(i.isEven) { y=pow(10,i/2); l=x%y; o=x/y; o=o-l/y; o3=o; for(int j=0;j<4;j++) { if(o%10==0) o=o/10; ...
http://rosettacode.org/wiki/Kaprekar_numbers
Kaprekar numbers
A positive integer is a Kaprekar number if: It is   1     (unity) The decimal representation of its square may be split once into two parts consisting of positive integers which sum to the original number. Note that a split resulting in a part consisting purely of 0s is not valid, as 0 is not considered positive. ...
#Elixir
Elixir
defmodule KaprekarNumber do def check(n), do: check(n, 10)   def check(1,_base), do: {"1", ""} def check(n, base) when rem(n*(n-1), (base-1)) != 0, do: false # casting out nine def check(n, base) do square = Integer.to_string(n*n, base) check(n, base, square, 1, String.length(square)-1) end   d...
http://rosettacode.org/wiki/JSON
JSON
Load a JSON string into a data structure. Also, create a new data structure and serialize it into JSON. Use objects and arrays (as appropriate for your language) and make sure your JSON is valid (https://jsonformatter.org).
#EGL
EGL
record familyMember person person; relationships relationship[]?; end   record person firstName string; lastName string; age int; end   record relationship relationshipType string; id int; end
http://rosettacode.org/wiki/JSON
JSON
Load a JSON string into a data structure. Also, create a new data structure and serialize it into JSON. Use objects and arrays (as appropriate for your language) and make sure your JSON is valid (https://jsonformatter.org).
#Elena
Elena
import extensions; import extensions'dynamic;   public program() { var json := "{ ""foo"": 1, ""bar"": [10, ""apples""] }";   var o := json.fromJson();   console.printLine("json.foo=",o.foo); console.printLine("json.bar=",o.bar) }
http://rosettacode.org/wiki/Joystick_position
Joystick position
The task is to determine the joystick position and represent this on the display via a crosshair. For a centred joystick, the crosshair should appear in the centre of the screen. If the joystick is pushed left or right, then the cross hair should move left or right according to the extent that the joystick is pushed. ...
#Tcl
Tcl
package require Tk 8.6 package require mkLibsdl   # This code assumes we're dealing with the first pair of axes on the first # joystick; modern joysticks are complex...   # Callback for all joystick activity proc display {joyDict} { global x y buttons message set axis -1 dict with joyDict { if {$joystick !...
http://rosettacode.org/wiki/Joystick_position
Joystick position
The task is to determine the joystick position and represent this on the display via a crosshair. For a centred joystick, the crosshair should appear in the centre of the screen. If the joystick is pushed left or right, then the cross hair should move left or right according to the extent that the joystick is pushed. ...
#Wren
Wren
import "input" for Keyboard, GamePad import "graphics" for Canvas, Color import "dome" for Window   var Buttons = [ "left", "right", "up", "down", "A", "B", "X", "Y", "back", "start", "guide", "leftshoulder", "rightshoulder" ]   var Symbols = ["L", "R", "U", "D", "A", "B", "X", "Y", "BK", "S", "G", "LS", "RS"] ...
http://rosettacode.org/wiki/Knight%27s_tour
Knight's tour
Task Problem: you have a standard 8x8 chessboard, empty but for a single knight on some square. Your task is to emit a series of legal knight moves that result in the knight visiting every square on the chessboard exactly once. Note that it is not a requirement that the tour be "closed"; that is, the knight need not e...
#Erlang
Erlang
  -module( knights_tour ).   -export( [display/1, solve/1, task/0] ).   display( Moves ) -> %% The knigh walks the moves {Position, Step_nr} order. %% Top left corner is {$a, 8}, Bottom right is {$h, 1}. io:fwrite( "Moves:" ), lists:foldl( fun display_moves/2, erlang:length(Moves), lists:keysort(2, Moves) ), io:nl...
http://rosettacode.org/wiki/Knuth_shuffle
Knuth shuffle
The   Knuth shuffle   (a.k.a. the Fisher-Yates shuffle)   is an algorithm for randomly shuffling the elements of an array. Task Implement the Knuth shuffle for an integer array (or, if possible, an array of any type). Specification Given an array items with indices ranging from 0 to last, the algorithm can be d...
#Egel
Egel
  import "prelude.eg" import "random.ego"   using System using List using Math   def swap = [ I J XX -> insert I (nth J XX) (insert J (nth I XX) XX) ]   def shuffle = [ XX -> let INDICES = reverse (fromto 0 ((length XX) - 1)) in let SWAPS = map [ I -> I (between 0 I) ] INDICES in fol...
http://rosettacode.org/wiki/K-means%2B%2B_clustering
K-means++ clustering
K-means++ clustering K-means This data was partitioned into 7 clusters using the K-means algorithm. The task is to implement the K-means++ algorithm. Produce a function which takes two arguments: the number of clusters K, and the dataset to classify. K is a positive integer and the dataset is a list of points in the C...
#Python
Python
from math import pi, sin, cos from collections import namedtuple from random import random, choice from copy import copy   try: import psyco psyco.full() except ImportError: pass     FLOAT_MAX = 1e100     class Point: __slots__ = ["x", "y", "group"] def __init__(self, x=0.0, y=0.0, group=0): ...
http://rosettacode.org/wiki/Julia_set
Julia set
Task Generate and draw a Julia set. Related tasks   Mandelbrot Set
#J
J
load '~addons/graphics/fvj4/complex_dynamics.ijs' pal2=: 255,~0,<.(254$1 0.8 0.6)*Hue 5r6*(i.%<:)254 g=: [: %: 0.3746j0.102863 0.132565j0.389103 _0.373935j_0.353777 1&p. view_image pal2;b=:g escapetc (10 255) 500 zl_clur _1.5 1.5j1.5
http://rosettacode.org/wiki/Julia_set
Julia set
Task Generate and draw a Julia set. Related tasks   Mandelbrot Set
#Java
Java
import javax.swing.*; import java.awt.*; import java.awt.image.BufferedImage;   public class JuliaSet extends JPanel { private static final int MAX_ITERATIONS = 300; private static final double ZOOM = 1; private static final double CX = -0.7; private static final double CY = 0.27015; private static ...
http://rosettacode.org/wiki/Knapsack_problem/Unbounded
Knapsack problem/Unbounded
A traveler gets diverted and has to make an unscheduled stop in what turns out to be Shangri La.   Opting to leave, he is allowed to take as much as he likes of the following items, so long as it will fit in his knapsack, and he can carry it. He knows that he can carry no more than   25   'weights' in total;   and tha...
#PowerShell
PowerShell
# Define the items to pack $Item = @( [pscustomobject]@{ Name = 'panacea'; Unit = 'vials'  ; value = 3000; Weight = 0.3; Volume = 0.025 } [pscustomobject]@{ Name = 'ichor'  ; Unit = 'ampules'; value = 1800; Weight = 0.2; Volume = 0.015 } [pscustomobject]@{ Name = 'gold'  ; Unit = 'bars'  ; value = 2500; ...
http://rosettacode.org/wiki/Keyboard_input/Obtain_a_Y_or_N_response
Keyboard input/Obtain a Y or N response
Task Obtain a valid   Y   or   N   response from the keyboard. The keyboard should be flushed, so that any outstanding key-presses are removed, preventing any existing   Y   or   N   key-press from being evaluated. The response should be obtained as soon as   Y   or   N   are pressed, and there should be no need t...
#Vlang
Vlang
import term.ui as tui   struct App { mut: tui &tui.Context = 0 }   fn event(e &tui.Event, x voidptr) { mut app := &App(x) app.tui.clear() app.tui.set_cursor_position(0, 0) app.tui.write('V term.input event viewer (type `y`, `Y`, `n`, or `N` to exit)\n\n') if e.typ == .key_down { mut cap := '' if !...
http://rosettacode.org/wiki/Keyboard_input/Obtain_a_Y_or_N_response
Keyboard input/Obtain a Y or N response
Task Obtain a valid   Y   or   N   response from the keyboard. The keyboard should be flushed, so that any outstanding key-presses are removed, preventing any existing   Y   or   N   key-press from being evaluated. The response should be obtained as soon as   Y   or   N   are pressed, and there should be no need t...
#Wee_Basic
Wee Basic
print 1 "Enter Y for yes, or N for no. (not case sensitive)" let loop=0 let keycode=0 while loop=0 let keycode=key() if keycode=121 let response$="y" let loop=1 elseif keycode=89 let response$="Y" let loop=1 elseif keycode=110 let response$="n" let loop=1 elseif keycode=78 let response$="N" let loop=1 endif wend print ...
http://rosettacode.org/wiki/Knapsack_problem/Continuous
Knapsack problem/Continuous
A thief burgles a butcher's shop, where he can select from some items. The thief knows the weights and prices of each items.   Because he has a knapsack with 15 kg maximal capacity, he wants to select the items such that he would have his profit maximized.   He may cut the items;   the item has a reduced price after...
#Prolog
Prolog
:- use_module(library(simplex)). % tuples (name, weights, value). knapsack :- L = [( beef, 3.8, 36), ( pork, 5.4, 43), ( ham, 3.6, 90), ( greaves, 2.4, 45), ( flitch, 4.0, 30), ( brawn, 2.5, 56), ( welt, 3.7, 67), ( salami, 3.0, 95), ...
http://rosettacode.org/wiki/Knapsack_problem/Bounded
Knapsack problem/Bounded
A tourist wants to make a good trip at the weekend with his friends. They will go to the mountains to see the wonders of nature.   So he needs some items during the trip.   Food, clothing, etc.   He has a good knapsack for carrying the things, but he knows that he can carry only 4 kg weight in his knapsack, because th...
#Swift
Swift
public struct KnapsackItem: Hashable { public var name: String public var weight: Int public var value: Int   public init(name: String, weight: Int, value: Int) { self.name = name self.weight = weight self.value = value } }   public func knapsack(items: [KnapsackItem], limit: Int) -> [KnapsackItem...
http://rosettacode.org/wiki/Jump_anywhere
Jump anywhere
Imperative programs conditional structures loops local jumps This task is to demonstrate a local jump and a global jump and the various other types of jumps that the language supports. For the purpose of this task, the jumps need not be used for a single purpose and you have the freedom to use these jumps for different...
#Kotlin
Kotlin
// version 1.0.6   fun main(args: Array<String>) { intArrayOf(4, 5, 6).forEach lambda@ { if (it == 5) return@lambda println(it) } println() loop@ for (i in 0 .. 3) { for (j in 0 .. 3) { if (i + j == 4) continue@loop if (i + j == 5) break@loop p...
http://rosettacode.org/wiki/Knapsack_problem/0-1
Knapsack problem/0-1
A tourist wants to make a good trip at the weekend with his friends. They will go to the mountains to see the wonders of nature, so he needs to pack well for the trip. He has a good knapsack for carrying things, but knows that he can carry a maximum of only 4kg in it,   and it will have to last the whole day. He cre...
#D
D
import std.stdio, std.algorithm, std.typecons, std.array, std.range;   struct Item { string name; int weight, value; }   Item[] knapsack01DinamicProgramming(immutable Item[] items, in int limit) pure nothrow @safe { auto tab = new int[][](items.length + 1, limit + 1);   foreach (immutable i, immutable it; items...
http://rosettacode.org/wiki/Kaprekar_numbers
Kaprekar numbers
A positive integer is a Kaprekar number if: It is   1     (unity) The decimal representation of its square may be split once into two parts consisting of positive integers which sum to the original number. Note that a split resulting in a part consisting purely of 0s is not valid, as 0 is not considered positive. ...
#Erlang
Erlang
  -mode(compile). -import(lists, [seq/2]).   kaprekar(1) -> true; kaprekar(N) when N < 1 -> false; kaprekar(N) -> Sq = N*N, if (N rem 9) =/= (Sq rem 9) -> false; true -> kaprekar(N, Sq, 10) end.   kaprekar(_, Sq, M) when (Sq div M) =:= 0 -> false; kaprekar(N, Sq, M) -> L = Sq div M, ...
http://rosettacode.org/wiki/JSON
JSON
Load a JSON string into a data structure. Also, create a new data structure and serialize it into JSON. Use objects and arrays (as appropriate for your language) and make sure your JSON is valid (https://jsonformatter.org).
#Emacs_Lisp
Emacs Lisp
(require 'cl-lib)   (cl-assert (fboundp 'json-parse-string)) (cl-assert (fboundp 'json-serialize))   (defvar example "{\"foo\": \"bar\", \"baz\": [1, 2, 3]}") (defvar example-object '((foo . "bar") (baz . [1 2 3])))   ;; decoding (json-parse-string example) ;=> #s(hash-table [...])) ;; using json.el-style options (json...
http://rosettacode.org/wiki/JSON
JSON
Load a JSON string into a data structure. Also, create a new data structure and serialize it into JSON. Use objects and arrays (as appropriate for your language) and make sure your JSON is valid (https://jsonformatter.org).
#Erlang
Erlang
  -module(json). -export([main/0]).   main() -> JSON = "{ \"firstName\": \"John\", \"lastName\": \"Smith\", \"age\": 25, \"address\": { \"streetAddress\": \"21 2nd Street\", \"city\": \"New York\", \"state\": \"NY\", \"postalCode\": \"10021\" }, ...
http://rosettacode.org/wiki/Joystick_position
Joystick position
The task is to determine the joystick position and represent this on the display via a crosshair. For a centred joystick, the crosshair should appear in the centre of the screen. If the joystick is pushed left or right, then the cross hair should move left or right according to the extent that the joystick is pushed. ...
#ZX_Spectrum_Basic
ZX Spectrum Basic
10 DIM o$(5) 20 LET xm=0: LET xx=31: REM screen limits 30 LET ym=0: LET yx=18 40 LET xo=16: LET yo=9: REM origin 50 LET xc=xo: LET yc=yo 60 PRINT AT yc,xc;" ": REM entry point for scan loop - blank cursor 70 LET xc=xo: LET yc=yo 80 LET t=IN 31 90 IF t=1 OR t=5 OR t=9 OR t=17 OR t=21 OR t=25 THEN LET xc=xx: LET o$(2)="R...
http://rosettacode.org/wiki/Knight%27s_tour
Knight's tour
Task Problem: you have a standard 8x8 chessboard, empty but for a single knight on some square. Your task is to emit a series of legal knight moves that result in the knight visiting every square on the chessboard exactly once. Note that it is not a requirement that the tour be "closed"; that is, the knight need not e...
#ERRE
ERRE
  ! ********************************************************************** ! * * ! * IL GIRO DEL CAVALLO - come collocare un cavallo su di una * ! * scacchiera n*n passando una sola volta * ! * ...