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Line 58: {{trans\|D}} <~~lang~~syntaxhighlight lang="11l">T.enum Piece EMPTY BLACK Line 138: printBoard(nm[0], blackQueens, whiteQueens) E print("No solution exists.\n")</~~lang~~syntaxhighlight> {{out}} Line 314: The program also can stop after printing a specified number of solutions, although the default is to print all solutions. (Commentary by the author: this program suffers similarly of slowness, in eliminating rotational equivalents, as does its Scheme ancestor. Some reasons: it uses backtracking and that is slow; it uses essentially the same inefficient storage format for solutions [one could for instance use integers], and it does not precompute rotational equivalents. However, it does satisfy the task requirements, and might be regarded as a good start. And it is can solve the m=5, n=6 case in practical time on a fast machine. m=7, n=7 is a more annoying case.) <~~lang~~syntaxhighlight lang="ats">(******************************************************************) #define ATS_DYNLOADFLAG 0 Line 1,260: end (*****************************************************************)</~~lang~~syntaxhighlight> {{out}} Line 1,306: =={{header\|C}}== {{trans\|C#}} <~~lang~~syntaxhighlight lang="c">#include <math.h> #include <stdbool.h> #include <stdio.h> Line 1,578: return EXIT_SUCCESS; }</~~lang~~syntaxhighlight> {{out}} <pre>1 black and 1 white queens on a 2 x 2 board: Line 1,745: =={{header\|C sharp\|C#}}== {{trans\|D}} <~~lang~~syntaxhighlight lang="csharp">using System; using System.Collections.Generic; Line 1,858: } } }</~~lang~~syntaxhighlight> {{out}} <pre>1 black and 1 white queens on a 2 x 2 board: Line 2,025: =={{header\|C++}}== {{trans\|D}} <~~lang~~syntaxhighlight lang="cpp">#include <iostream> #include <vector> Line 2,139: return 0; }</~~lang~~syntaxhighlight> {{out}} <pre>1 black and 1 white queens on a 2 x 2 board: Line 2,306: =={{header\|D}}== {{trans\|Go}} <~~lang~~syntaxhighlight lang="d">import std.array; import std.math; import std.stdio; Line 2,417: } } }</~~lang~~syntaxhighlight> {{out}} <pre>1 black and 1 white queens on a 2 x 2 board: Line 2,584: =={{header\|Fortran}}== {{works with\|gfortran\|11.2.1}} The example demonstrates modern Fortran’s capabilities for integer bit manipulation, by using large machine integers (and their entire bitrange) as bitmaps to represent queen armies. Complicated (but nevertheless single-statement) expressions of such integers represent such operations as rotating a chessboard and checking for any attacks. There are two Fortran programs and a driver script. One program generates a Fortran module for basic operations; the other program (which must be linked with the generated module) does the actual work. The driver script is for Unix shell. Line 2,589 ⟶ 2,592: Here is the first program, '''peaceful_queens_elements_generator.f90''', which generates code (specialized for given m and n) to deal with the representations of the armies as integers: <~~lang~~syntaxhighlight lang="fortran">program peaceful_queens_elements_generator use, intrinsic :: iso_fortran_env, only: int64 use, intrinsic :: iso_fortran_env, only: error_unit Line 3,404 ⟶ 3,407: end subroutine fill_queen_masks end program peaceful_queens_elements_generator</~~lang~~syntaxhighlight> Here is the second program, '''peaceful_queens.f90''': <~~lang~~syntaxhighlight lang="fortran">module peaceful_queens_support use, non_intrinsic :: peaceful_queens_elements Line 3,719 ⟶ 3,722: & num_solutions, armies1, armies2) end program peaceful_queens</~~lang~~syntaxhighlight> Here is the driver script: <~~lang~~syntaxhighlight lang="sh">#!/bin/sh # # Driver script for peaceful_queens in Fortran. Line 3,766 ⟶ 3,769: ${FC} ${FCFLAGS} -c peaceful_queens.f90 && ${FC} ${FCFLAGS} -o peaceful_queens peaceful_queens_elements.o peaceful_queens.o && if test x"${RUN_IT}" = xyes; then time ./peaceful_queens ${SHOW_EQUIVALENTS}; else :; fi</~~lang~~syntaxhighlight> {{out}} Line 3,996 ⟶ 3,999: It would be instructive to save and examine the generated '''peaceful_queens_elements.f90''' files. I leave that as an exercise for the reader. :) =={{header\|FreeBASIC}}== <syntaxhighlight lang="vbnet">Type posicion x As Integer y As Integer End Type Type pieza empty As Integer black As Integer white As Integer End Type Function isAttacking(q As posicion, posic As posicion) As Integer Return (q.x = posic.x Or q.y = posic.y Or Abs(q.x - posic.x) = Abs(q.y - posic.y)) End Function Sub place(m As Integer, n As Integer, blackQueens() As posicion, whiteQueens() As posicion, Byref result As Integer) If m = 0 Then result = -1 Exit Sub End If Dim As Integer placingBlack = -1 Dim As Integer i, j, k, equalposicion Dim As Boolean inner For i = 0 To n-1 For j = 0 To n-1 Dim As posicion posic = Type<posicion>(i, j) inner = False For k = Lbound(blackQueens) To Ubound(blackQueens) equalposicion = (blackQueens(k).x = posic.x And blackQueens(k).y = posic.y) If equalposicion Or (Not placingBlack And isAttacking(blackQueens(k), posic)) Then inner = True Exit For End If Next If Not inner Then For k = Lbound(whiteQueens) To Ubound(whiteQueens) equalposicion = (whiteQueens(k).x = posic.x And whiteQueens(k).y = posic.y) If equalposicion Or (placingBlack And isAttacking(whiteQueens(k), posic)) Then inner = True Exit For End If Next If Not inner Then If placingBlack Then Redim Preserve blackQueens(Ubound(blackQueens) + 1) blackQueens(Ubound(blackQueens)) = posic placingBlack = 0 Else Redim Preserve whiteQueens(Ubound(whiteQueens) + 1) whiteQueens(Ubound(whiteQueens)) = posic place(m-1, n, blackQueens(), whiteQueens(), result) If result Then Exit Sub Redim Preserve blackQueens(Ubound(blackQueens) - 1) Redim Preserve whiteQueens(Ubound(whiteQueens) - 1) placingBlack = -1 End If End If End If Next Next If Not placingBlack Then Redim Preserve blackQueens(Ubound(blackQueens) - 1) result = 0 End Sub Sub printBoard(n As Integer, blackQueens() As posicion, whiteQueens() As posicion) Dim As Integer board(n n) Dim As Integer i, j, k For i = Lbound(blackQueens) To Ubound(blackQueens) board(blackQueens(i).x * n + blackQueens(i).y) = 1 Next For i = Lbound(whiteQueens) To Ubound(whiteQueens) board(whiteQueens(i).x * n + whiteQueens(i).y) = 2 Next For i = 0 To nn-1 If i Mod n = 0 And i <> 0 Then Print Select Case board(i) Case 1 Print "B "; Case 2 Print "W "; Case Else j = i \ n k = i - j n If j Mod 2 = k Mod 2 Then Print Chr(253); " "; Else Print Chr(252); " "; End If End Select Next i Print End Sub Dim As posicion nms(23) = { _ Type<posicion>(2, 1), Type<posicion>(3, 1), Type<posicion>(3, 2), Type<posicion>(4, 1), Type<posicion>(4, 2), Type<posicion>(4, 3), _ Type<posicion>(5, 1), Type<posicion>(5, 2), Type<posicion>(5, 3), Type<posicion>(5, 4), Type<posicion>(5, 5), _ Type<posicion>(6, 1), Type<posicion>(6, 2), Type<posicion>(6, 3), Type<posicion>(6, 4), Type<posicion>(6, 5), Type<posicion>(6, 6), _ Type<posicion>(7, 1), Type<posicion>(7, 2), Type<posicion>(7, 3), Type<posicion>(7, 4), Type<posicion>(7, 5), Type<posicion>(7, 6), Type<posicion>(7, 7) } For i As Integer = Lbound(nms) To Ubound(nms) Print Chr(10); nms(i).y; " black and "; nms(i).y; " white queens on a "; nms(i).x; " x "; nms(i).x; " board:" Dim As posicion blackQueens(0) Dim As posicion whiteQueens(0) Dim As Integer result place(nms(i).y, nms(i).x, blackQueens(), whiteQueens(), result) If result Then printBoard(nms(i).x, blackQueens(), whiteQueens()) Else Print "No solution exists." End If Next i Sleep</syntaxhighlight> {{out}} <pre> 1 black and 1 white queens on a 2 x 2 board: No solution exists. 1 black and 1 white queens on a 3 x 3 board: ² ³ ² ³ ² B W ³ ² 2 black and 2 white queens on a 3 x 3 board: ² B ² ³ ² ³ ² ³ W 1 black and 1 white queens on a 4 x 4 board: ² ³ ² ³ ³ ² B ² W ³ ² ³ ³ ² ³ ² 2 black and 2 white queens on a 4 x 4 board: ² B ² ³ ³ ² ³ W ² ³ ² ³ ³ ² ³ ² 3 black and 3 white queens on a 4 x 4 board: B ³ ² ³ ³ ² W ² ² ³ ² ³ ³ ² ³ ² 1 black and 1 white queens on a 5 x 5 board: ² ³ ² ³ ² ³ ² B ² ³ W ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² 2 black and 2 white queens on a 5 x 5 board: ² B ² ³ ² ³ ² ³ W ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² 3 black and 3 white queens on a 5 x 5 board: B ³ ² ³ ² ³ ² W ² ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² 4 black and 4 white queens on a 5 x 5 board: ² ³ ² ³ B W ² ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² 5 black and 5 white queens on a 5 x 5 board: ² ³ B ³ ² ³ ² ³ ² W ² ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² 1 black and 1 white queens on a 6 x 6 board: ² ³ ² ³ ² ³ ³ ² B ² ³ ² W ³ ² ³ ² ³ ³ ² ³ ² ³ ² ² ³ ² ³ ² ³ ³ ² ³ ² ³ ² 2 black and 2 white queens on a 6 x 6 board: ² B ² ³ ² ³ ³ ² ³ W ³ ² ² ³ ² ³ ² ³ ³ ² ³ ² ³ ² ² ³ ² ³ ² ³ ³ ² ³ ² ³ ² 3 black and 3 white queens on a 6 x 6 board: B ³ ² ³ ² ³ ³ ² W ² ³ ² ² ³ ² ³ ² ³ ³ ² ³ ² ³ ² ² ³ ² ³ ² ³ ³ ² ³ ² ³ ² 4 black and 4 white queens on a 6 x 6 board: ² ³ ² ³ B ³ W ² ³ ² ³ ² ² ³ ² ³ ² ³ ³ ² ³ ² ³ ² ² ³ ² ³ ² ³ ³ ² ³ ² ³ ² 5 black and 5 white queens on a 6 x 6 board: ² ³ B ³ ² ³ ³ ² ³ ² W ² ² ³ ² ³ ² ³ ³ ² ³ ² ³ ² ² ³ ² ³ ² ³ ³ ² ³ ² ³ ² 6 black and 6 white queens on a 6 x 6 board: B ³ ² ³ ² ³ ³ ² W ² ³ ² ² ³ ² ³ ² ³ ³ ² ³ ² ³ ² ² ³ ² ³ ² ³ ³ ² ³ ² ³ ² 1 black and 1 white queens on a 7 x 7 board: ² ³ ² ³ ² ³ ² ³ ² B ² ³ ² ³ W ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² 2 black and 2 white queens on a 7 x 7 board: ² B ² ³ ² ³ ² ³ ² ³ W ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² 3 black and 3 white queens on a 7 x 7 board: B ³ ² ³ ² ³ ² ³ ² W ² ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² 4 black and 4 white queens on a 7 x 7 board: ² ³ ² ³ B ³ ² W ² ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² 5 black and 5 white queens on a 7 x 7 board: ² ³ B ³ ² ³ ² ³ ² ³ ² W ² ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² 6 black and 6 white queens on a 7 x 7 board: B ³ ² ³ ² ³ ² ³ ² W ² ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² 7 black and 7 white queens on a 7 x 7 board: ² ³ ² ³ B ³ ² W ² ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² ³ ² ³ ²</pre> =={{header\|Go}}== Line 4,001 ⟶ 4,299: Textual rather than HTML output. Whilst the unicode symbols for the black and white queens are recognized by the Ubuntu 16.04 terminal, I found it hard to visually distinguish between them so I've used 'B' and 'W' instead. <~~lang~~syntaxhighlight lang="go">package main import "fmt" Line 4,125 ⟶ 4,423: } } }</~~lang~~syntaxhighlight> {{out}} Line 4,297 ⟶ 4,595: =={{header\|Java}}== {{trans\|Kotlin}} <~~lang~~syntaxhighlight lang="java">import java.util.ArrayList; import java.util.Arrays; import java.util.List; Line 4,444 ⟶ 4,742: } } }</~~lang~~syntaxhighlight> {{out}} <pre>1 black and 1 white queens on a 2 x 2 board: Line 4,608 ⟶ 4,906: B • B • ◦ • ◦ • ◦ • ◦ W ◦ • </pre> =={{header\|jq}}== '''Adapted from [[#Wren\|Wren]]''' '''Works with jq, the C implementation of jq''' '''Works with gojq, the Go implementation of jq''' In the following, positions on the chessboard are represented by {x,y} objects. <syntaxhighlight lang="jq"> # Is the queen at position . attacking the position $pos ? def isAttacking($pos): .x == $pos.x or .y == $pos.y or (((.x - $pos.x)\|length) == ((.y - $pos.y)\|length)); # i.e. abs # Place $q black and $q white queens on an $n$n board, # where .blackQueens holds the positions of existing black Queens, # and similarly for .whiteQueens. # input: {blackQueens, whiteQueens} # output: updated input on success, otherwise null. def place($queens; $n): def place($q): if $q == 0 then .ok = true else .placingBlack = true \| first( foreach range(0; $n) as $i (.; foreach range(0; $n) as $j (.; {x:$i, y:$j} as $pos \| .placingBlack as $placingBlack \| if any( .blackQueens[], .whiteQueens[]; ((.x == $pos.x) and (.y == $pos.y))) then . # failure elif .placingBlack then if any( .whiteQueens[]; isAttacking($pos) ) then . else .blackQueens += [$pos] \| .placingBlack = false end elif any( .blackQueens[]; isAttacking($pos) ) then . else .whiteQueens += [$pos] \| place($q-1) as $place \| if $place then $place # success else .blackQueens \|= .[:-1] \| .whiteQueens \|= .[:-1] \| .placingBlack = true end end \| if $i == $n-1 and $j == $n-1 then .ok = false end ); select(.ok) ) ) // null end; {blackQueens: [], whiteQueens: [] } \| place($queens); # Input {blackQueens, whiteQueens} def printBoard($n): [range(0; $n) \| 0] as $row \| .board = [range(0; $n) \| $row] \| reduce .blackQueens[] as $queen (.; .board[$queen.x][$queen.y] = "B ") \| reduce .whiteQueens[] as $queen (.; .board[$queen.x][$queen.y] = "W ") \| foreach range(0; $n) as $i (.; reduce range(0; $n) as $j (.row=""; .board[$i][$j] as $b \| .row += (if $b != 0 then $b elif $i%2 == $j%2 then "• " else "◦ " end) ) ) \| .row; # Use an object {squares, queens} to record the task: # $squares is the number of squares on each side of the board, # and $queens is the number of queens of each color. def Task($squares; $queens): {$squares, $queens}; def tasks: [ Task(2; 1), Task(3; 1), Task(3; 2), Task(4; 1), Task(4; 2), Task(4; 3), Task(5; 1), Task(5; 2), Task(5; 3), Task(5; 4), Task(5; 5), Task(6; 1), Task(6; 2), Task(6; 3), Task(6; 4), Task(6; 5), Task(6; 6), Task(7; 1), Task(7; 2), Task(7; 3), Task(7; 4), Task(7; 5), Task(7; 6), Task(7; 7) ]; tasks[] as $t \| "\($t.queens) black and \($t.queens) white queens on a \($t.squares) x \($t.squares) board:", ((place($t.queens; $t.squares) \| select(.) \| printBoard($t.squares)) // "No solution exists."), "" </syntaxhighlight> {{output}} See [[#Wren\|Wren]]. =={{header\|Julia}}== GUI version, uses the Gtk library. The place! function is condensed from the C# example. <~~lang~~syntaxhighlight lang="julia">using Gtk struct Position Line 4,716 ⟶ 5,108: peacefulqueenapp() </syntaxhighlight> ~~</lang>~~ =={{header\|Kotlin}}== {{trans\|D}} <~~lang~~syntaxhighlight lang="scala">import kotlin.math.abs enum class Piece { Line 4,822 ⟶ 5,214: } } }</~~lang~~syntaxhighlight> {{out}} <pre>1 black and 1 white queens on a 2 x 2 board: Line 4,988 ⟶ 5,380: =={{header\|Mathematica}}/{{header\|Wolfram Language}}== <~~lang~~syntaxhighlight ~~Mathematica~~lang="mathematica">ClearAll[ValidSpots, VisibleByQueen, SolveQueen, GetSolution] VisualizeState[state_] := Module[{q, cells}, q = MapIndexed[If[#["q"] == -1, {}, Text[Style[#["q"], 24], #2]] &, state, {2}]; Line 5,031 ⟶ 5,423: ] GetSolution[8, 4, 3]( Solves placing 3 armies of each 4 queens on an 88 board) GetSolution[5, 4, 2](* Solves placing 2 armies of each 4 queens on an 55 board)</~~lang~~syntaxhighlight> {{out}} <pre>[Graphical object] Line 5,054 ⟶ 5,446: Almost a direct translation except for "printBoard" where we have chosen to use a sequence of sequences to simplify the code. <~~lang~~syntaxhighlight ~~Nim~~lang="nim">import sequtils, strformat type Line 5,127 ⟶ 5,519: printBoard(n, blackQueens, whiteQueens) else: echo "No solution exists.\n"</~~lang~~syntaxhighlight> {{out}} Line 5,296 ⟶ 5,688: =={{header\|Perl}}== ===Terse=== <~~lang~~syntaxhighlight lang="perl">use strict; use warnings; Line 5,314 ⟶ 5,706: (my $have = tr/WB//) < $m * 2 or exit !print "Solution to $m $n\n\n$_"; place( s/-\G/ qw(W B)[$have % 2] /er ) while /-/g; # place next queen }</~~lang~~syntaxhighlight> {{out}} <pre>Solution to 4 5 Line 5,325 ⟶ 5,717: ===Verbose=== A refactored version of the same code, with fancier output. <~~lang~~syntaxhighlight lang="perl">use strict; use warnings; use feature 'say'; Line 5,376 ⟶ 5,768: say $solution ? sprintf "Solution to $m $n\n\n%s", map { s/(.)/$1 /gm; s/B /♛/gm; s/W /♕/gmr } $solution : "No solution to $m $n";</~~lang~~syntaxhighlight> {{out}} <pre>Solution to 4 5 Line 5,389 ⟶ 5,781: {{trans\|Go}} {{trans\|Python}} You can run this online [http://phix.x10.mx/p2js/QueenArmies.htm here]. ~~<lang Phix>-- demo\rosetta\Queen_Armies.exw~~ <!--<syntaxhighlight lang="phix">(phixonline)--> ~~string html = ""~~ <span style="color: #000080;font-style:italic;">-- ~~constant as_html = true~~ -- demo\rosetta\Queen_Armies.exw ~~constant queens = {``,~~ -- ============================= ~~`♛`,~~ --</span> ~~`<font color="green">♕</font>`,~~ <span style="color: #008080;">with</span> `<span style="color:~~red~~ #008080;">?javascript_semantics</span>`} <span style="color: #7060A8;">requires</span><span style="color: #0000FF;">(</span><span style="color: #008000;">"1.0.2"</span><span style="color: #0000FF;">)</span> <span style="color: #000080;font-style:italic;">-- (puts(fn,x,false) for p2js.js)</span> <span style="color: #004080;">string</span> <span style="color: #000000;">html</span> <span style="color: #0000FF;">=</span> <span style="color: #008000;">""</span> ~~procedure showboard(integer n, sequence blackqueens, whitequeens)~~ <span style="color: #008080;">constant</span> <span style="color: #000000;">as_html</span> <span style="color: #0000FF;">=</span> <span style="color: #004600;">true</span> ~~sequence board = repeat(repeat('-',n),n)~~ <span style="color: #008080;">constant</span> <span style="color: #000000;">queens</span> <span style="color: #0000FF;">=</span> <span style="color: #0000FF;">{</span><span style="color: #008000;">``</span><span style="color: #0000FF;">,</span> ~~for i=1 to length(blackqueens) do~~ <span style="color: #008000;">`♛`</span><span style="color: #0000FF;">,</span> ~~integer {qi,qj} = blackqueens[i]~~ <span style="color: #008000;">`<font color="green">♕</font>`</span><span style="color: #0000FF;">,</span> ~~board[qi,qj] = 'B'~~ <span style="color: #008000;">`<span style="color:red">?</span>`</span><span style="color: #0000FF;">}</span> ~~{qi,qj} = whitequeens[i]~~ ~~board[qi,qj] = 'W'~~ <span style="color: #008080;">procedure</span> <span style="color: #000000;">showboard</span><span style="color: #0000FF;">(</span><span style="color: #004080;">integer</span> <span style="color: #000000;">n</span><span style="color: #0000FF;">,</span> <span style="color: #004080;">sequence</span> <span style="color: #000000;">blackqueens</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">whitequeens</span><span style="color: #0000FF;">)</span> ~~end for~~ <span style="color: #004080;">sequence</span> <span style="color: #000000;">board</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">repeat</span><span style="color: #0000FF;">(</span><span style="color: #7060A8;">repeat</span><span style="color: #0000FF;">(</span><span style="color: #008000;">'-'</span><span style="color: #0000FF;">,</span><span style="color: #000000;">n</span><span style="color: #0000FF;">),</span><span style="color: #000000;">n</span><span style="color: #0000FF;">)</span> ~~if as_html then~~ <span style="color: #008080;">for</span> <span style="color: #000000;">i</span><span style="color: #0000FF;">=</span><span style="color: #000000;">1</span> <span style="color: #008080;">to</span> <span style="color: #7060A8;">length</span><span style="color: #0000FF;">(</span><span style="color: #000000;">blackqueens</span><span style="color: #0000FF;">)</span> <span style="color: #008080;">do</span> ~~string out = sprintf("<br><b>## %d black and %d white queens on a %d-by-%d board</b><br>\n",~~ <span style="color: #004080;">integer</span> <span style="color: #0000FF;">{</span><span style="color: #000000;">qi</span><span style="color: #0000FF;">,</span><span style="color: #000000;">qj</span><span style="color: #0000FF;">}</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">blackqueens</span><span style="color: #0000FF;">[</span><span style="color: #000000;">i</span><span style="color: #0000FF;">]</span> ~~{length(blackqueens),length(whitequeens),n,n}),~~ <span style="color: #000000;">board</span><span style="color: #0000FF;">[</span><span style="color: #000000;">qi</span><span style="color: #0000FF;">,</span><span style="color: #000000;">qj</span><span style="color: #0000FF;">]</span> <span style="color: #0000FF;">=</span> <span style="color: #008000;">'B'</span> ~~tbl = ""~~ <span style="color: #0000FF;">{</span><span style="color: #000000;">qi</span><span style="color: #0000FF;">,</span><span style="color: #000000;">qj</span><span style="color: #0000FF;">}</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">whitequeens</span><span style="color: #0000FF;">[</span><span style="color: #000000;">i</span><span style="color: #0000FF;">]</span> ~~out &= "<table style=\"font-weight:bold\">\n "~~ <span style="color: #000000;">board</span><span style="color: #0000FF;">[</span><span style="color: #000000;">qi</span><span style="color: #0000FF;">,</span><span style="color: #000000;">qj</span><span style="color: #0000FF;">]</span> <span style="color: #0000FF;">=</span> <span style="color: #008000;">'W'</span> ~~for x=1 to n do~~ <span style="color: #008080;">end</span> <span style="color: #008080;">for</span> ~~for y=1 to n do~~ <span style="color: #008080;">if</span> <span style="color: #000000;">as_html</span> <span style="color: #008080;">then</span> ~~if y=1 then tbl &= " </tr>\n <tr valign=\"middle\" align=\"center\">\n" end if~~ <span style="color: #004080;">string</span> <span style="color: #000000;">out</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">sprintf</span><span style="color: #0000FF;">(</span><span style="color: #008000;">"<br><b>## %d black and %d white queens on a %d-by-%d board</b><br>\n"</span><span style="color: #0000FF;">,</span> ~~integer xw = find({x,y},blackqueens)!=0,~~ <span style="color: #0000FF;">{</span><span style="color: #7060A8;">length</span><span style="color: #0000FF;">(</span><span style="color: #000000;">blackqueens</span><span style="color: #0000FF;">),</span><span style="color: #7060A8;">length</span><span style="color: #0000FF;">(</span><span style="color: #000000;">whitequeens</span><span style="color: #0000FF;">),</span><span style="color: #000000;">n</span><span style="color: #0000FF;">,</span><span style="color: #000000;">n</span><span style="color: #0000FF;">}),</span> ~~xb = find({x,y},whitequeens)!=0,~~ <span style="color: #000000;">tbl</span> <span style="color: #0000FF;">=</span> <span style="color: #008000;">""</span> ~~dx = xw+xb2+1~~ <span style="color: #000000;">out</span> <span style="color: #0000FF;">&=</span> <span style="color: #008000;">"<table style=\"font-weight:bold\">\n "</span> ~~string ch = queens[dx],~~ <span style="color: #008080;">for</span> <span style="color: #000000;">x</span><span style="color: #0000FF;">=</span><span style="color: #000000;">1</span> <span style="color: #008080;">to</span> <span style="color: #000000;">n</span> <span style="color: #008080;">do</span> ~~bg = iff(mod(x+y,2)?"":` bgcolor="silver"`)~~ <span style="color: #008080;">for</span> <span style="color: #000000;">y</span><span style="color: #0000FF;">=</span><span style="color: #000000;">1</span> <span style="color: #008080;">to</span> <span style="color: #000000;">n</span> <span style="color: #008080;">do</span> ~~tbl &= sprintf(" <td style=\"width:14pt; height:14pt;\"%s>%s</td>\n",{bg,ch})~~ <span style="color: #008080;">if</span> <span style="color: #000000;">y</span><span style="color: #0000FF;">=</span><span style="color: #000000;">1</span> <span style="color: #008080;">then</span> <span style="color: #000000;">tbl</span> <span style="color: #0000FF;">&=</span> <span style="color: #008000;">" </tr>\n <tr valign=\"middle\" align=\"center\">\n"</span> <span style="color: #008080;">end</span> <span style="color: #008080;">if</span> ~~end for~~ <span style="color: #004080;">integer</span> <span style="color: #000000;">xw</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">find</span><span style="color: #0000FF;">({</span><span style="color: #000000;">x</span><span style="color: #0000FF;">,</span><span style="color: #000000;">y</span><span style="color: #0000FF;">},</span><span style="color: #000000;">blackqueens</span><span style="color: #0000FF;">)!=</span><span style="color: #000000;">0</span><span style="color: #0000FF;">,</span> ~~end for~~ <span style="color: #000000;">xb</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">find</span><span style="color: #0000FF;">({</span><span style="color: #000000;">x</span><span style="color: #0000FF;">,</span><span style="color: #000000;">y</span><span style="color: #0000FF;">},</span><span style="color: #000000;">whitequeens</span><span style="color: #0000FF;">)!=</span><span style="color: #000000;">0</span><span style="color: #0000FF;">,</span> ~~out &= tbl[11..$]~~ <span style="color: #000000;">dx</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">xw</span><span style="color: #0000FF;">+</span><span style="color: #000000;">xb</span><span style="color: #0000FF;"></span><span style="color: #000000;">2</span><span style="color: #0000FF;">+</span><span style="color: #000000;">1</span> ~~out &= " </tr>\n</table>\n<br>\n"~~ <span style="color: #004080;">string</span> <span style="color: #000000;">ch</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">queens</span><span style="color: #0000FF;">[</span><span style="color: #000000;">dx</span><span style="color: #0000FF;">],</span> ~~html &= out~~ <span style="color: #000000;">bg</span> <span style="color: #0000FF;">=</span> <span style="color: #008080;">iff</span><span style="color: #0000FF;">(</span><span style="color: #7060A8;">mod</span><span style="color: #0000FF;">(</span><span style="color: #000000;">x</span><span style="color: #0000FF;">+</span><span style="color: #000000;">y</span><span style="color: #0000FF;">,</span><span style="color: #000000;">2</span><span style="color: #0000FF;">)?</span><span style="color: #008000;">""</span><span style="color: #0000FF;">:</span><span style="color: #008000;">` bgcolor="silver"`</span><span style="color: #0000FF;">)</span> ~~else~~ <span style="color: #000000;">tbl</span> <span style="color: #0000FF;">&=</span> <span style="color: #7060A8;">sprintf</span><span style="color: #0000FF;">(</span><span style="color: #008000;">" <td style=\"width:14pt; height:14pt;\"%s>%s</td>\n"</span><span style="color: #0000FF;">,{</span><span style="color: #000000;">bg</span><span style="color: #0000FF;">,</span><span style="color: #000000;">ch</span><span style="color: #0000FF;">})</span> ~~integer b = length(blackqueens),~~ <span style="color: #008080;">end</span> w<span style="color: ~~length(whitequeens)~~#008080;">for</span> <span style="color: #008080;">end</span> <span style="color: #008080;">for</span> ~~printf(1,"%d black and %d white queens on a %d x %d board:\n", {b, w, n, n})~~ <span style="color: #000000;">out</span> <span style="color: #0000FF;">&=</span> <span style="color: #000000;">tbl</span><span style="color: #0000FF;">[</span><span style="color: #000000;">11</span><span style="color: #0000FF;">..$]</span> ~~puts(1,join(board,"\n")&"\n")~~ <span style="color: #000000;">out</span> <span style="color: #0000FF;">&=</span> <span style="color: #008000;">" </tr>\n</table>\n<br>\n"</span> ~~-- ?{n,blackqueens, whitequeens}~~ <span style="color: #000000;">html</span> <span style="color: #0000FF;">&=</span> <span style="color: #000000;">out</span> ~~end if~~ <span style="color: #008080;">else</span> ~~end procedure~~ <span style="color: #004080;">integer</span> <span style="color: #000000;">b</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">length</span><span style="color: #0000FF;">(</span><span style="color: #000000;">blackqueens</span><span style="color: #0000FF;">),</span> <span style="color: #000000;">w</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">length</span><span style="color: #0000FF;">(</span><span style="color: #000000;">whitequeens</span><span style="color: #0000FF;">)</span> ~~function isAttacking(sequence queen, pos)~~ <span style="color: #7060A8;">printf</span><span style="color: #0000FF;">(</span><span style="color: #000000;">1</span><span style="color: #0000FF;">,</span><span style="color: #008000;">"%d black and %d white queens on a %d x %d board:\n"</span><span style="color: #0000FF;">,</span> <span style="color: #0000FF;">{</span><span style="color: #000000;">b</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">w</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">n</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">n</span><span style="color: #0000FF;">})</span> ~~integer {qi,qj} = queen, {pi,pj} = pos~~ <span style="color: #7060A8;">puts</span><span style="color: #0000FF;">(</span><span style="color: #000000;">1</span><span style="color: #0000FF;">,</span><span style="color: #7060A8;">join</span><span style="color: #0000FF;">(</span><span style="color: #000000;">board</span><span style="color: #0000FF;">,</span><span style="color: #008000;">"\n"</span><span style="color: #0000FF;">)&</span><span style="color: #008000;">"\n"</span><span style="color: #0000FF;">)</span> ~~return qi=pi or qj=pj or abs(qi-pi)=abs(qj-pj)~~ <span style="color: #000080;font-style:italic;">-- ?{n,blackqueens, whitequeens}</span> ~~end function~~ <span style="color: #008080;">end</span> <span style="color: #008080;">if</span> <span style="color: #008080;">end</span> <span style="color: #008080;">procedure</span> ~~function place(integer m, n, sequence blackqueens = {}, whitequeens = {})~~ ~~if m == 0 then showboard(n,blackqueens,whitequeens) return true end if~~ <span style="color: #008080;">function</span> <span style="color: #000000;">isAttacking</span><span style="color: #0000FF;">(</span><span style="color: #004080;">sequence</span> <span style="color: #000000;">queen</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">pos</span><span style="color: #0000FF;">)</span> ~~bool placingBlack := true~~ <span style="color: #004080;">integer</span> <span style="color: #0000FF;">{</span><span style="color: #000000;">qi</span><span style="color: #0000FF;">,</span><span style="color: #000000;">qj</span><span style="color: #0000FF;">}</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">queen</span><span style="color: #0000FF;">,</span> <span style="color: #0000FF;">{</span><span style="color: #000000;">pi</span><span style="color: #0000FF;">,</span><span style="color: #000000;">pj</span><span style="color: #0000FF;">}</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">pos</span> ~~for i=1 to n do~~ <span style="color: #008080;">return</span> <span style="color: #000000;">qi</span><span style="color: #0000FF;">=</span><span style="color: #000000;">pi</span> <span style="color: #008080;">or</span> <span style="color: #000000;">qj</span><span style="color: #0000FF;">=</span><span style="color: #000000;">pj</span> <span style="color: #008080;">or</span> <span style="color: #7060A8;">abs</span><span style="color: #0000FF;">(</span><span style="color: #000000;">qi</span><span style="color: #0000FF;">-</span><span style="color: #000000;">pi</span><span style="color: #0000FF;">)=</span><span style="color: #7060A8;">abs</span><span style="color: #0000FF;">(</span><span style="color: #000000;">qj</span><span style="color: #0000FF;">-</span><span style="color: #000000;">pj</span><span style="color: #0000FF;">)</span> ~~for j=1 to n do~~ <span style="color: #008080;">end</span> <span style="color: #008080;">function</span> ~~sequence pos := {i, j}~~ ~~for q=1 to length(blackqueens) do~~ <span style="color: #008080;">function</span> <span style="color: #000000;">place</span><span style="color: #0000FF;">(</span><span style="color: #004080;">integer</span> <span style="color: #000000;">m</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">n</span><span style="color: #0000FF;">,</span> <span style="color: #004080;">sequence</span> <span style="color: #000000;">blackqueens</span> <span style="color: #0000FF;">=</span> <span style="color: #0000FF;">{},</span> <span style="color: #000000;">whitequeens</span> <span style="color: #0000FF;">=</span> <span style="color: #0000FF;">{})</span> ~~sequence queen := blackqueens[q]~~ <span style="color: #008080;">if</span> <span style="color: #000000;">m</span> <span style="color: #0000FF;">==</span> <span style="color: #000000;">0</span> <span style="color: #008080;">then</span> <span style="color: #000000;">showboard</span><span style="color: #0000FF;">(</span><span style="color: #000000;">n</span><span style="color: #0000FF;">,</span><span style="color: #000000;">blackqueens</span><span style="color: #0000FF;">,</span><span style="color: #000000;">whitequeens</span><span style="color: #0000FF;">)</span> <span style="color: #008080;">return</span> <span style="color: #004600;">true</span> <span style="color: #008080;">end</span> <span style="color: #008080;">if</span> ~~if queen == pos or ((not placingBlack) and isAttacking(queen, pos)) then~~ <span style="color: #004080;">bool</span> <span style="color: #000000;">placingBlack</span> <span style="color: #0000FF;">:=</span> <span style="color: #004600;">true</span> ~~pos = {}~~ <span style="color: #008080;">for</span> <span style="color: #000000;">i</span><span style="color: #0000FF;">=</span><span style="color: #000000;">1</span> <span style="color: #008080;">to</span> <span style="color: #000000;">n</span> <span style="color: #008080;">do</span> ~~exit~~ <span style="color: #008080;">for</span> <span style="color: #000000;">j</span><span style="color: #0000FF;">=</span><span style="color: #000000;">1</span> <span style="color: #008080;">to</span> <span style="color: #000000;">n</span> <span style="color: #008080;">do</span> ~~end if~~ <span style="color: #004080;">sequence</span> <span style="color: #000000;">pos</span> <span style="color: #0000FF;">:=</span> <span style="color: #0000FF;">{</span><span style="color: #000000;">i</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">j</span><span style="color: #0000FF;">}</span> ~~end for~~ <span style="color: #008080;">for</span> <span style="color: #000000;">q</span><span style="color: #0000FF;">=</span><span style="color: #000000;">1</span> <span style="color: #008080;">to</span> <span style="color: #7060A8;">length</span><span style="color: #0000FF;">(</span><span style="color: #000000;">blackqueens</span><span style="color: #0000FF;">)</span> <span style="color: #008080;">do</span> ~~if pos!={} then~~ <span style="color: #004080;">sequence</span> <span style="color: #000000;">queen</span> <span style="color: #0000FF;">:=</span> <span style="color: #000000;">blackqueens</span><span style="color: #0000FF;">[</span><span style="color: #000000;">q</span><span style="color: #0000FF;">]</span> ~~for q=1 to length(whitequeens) do~~ <span style="color: #008080;">if</span> <span style="color: #000000;">queen</span> <span style="color: #0000FF;">==</span> <span style="color: #000000;">pos</span> <span style="color: #008080;">or</span> <span style="color: #0000FF;">((</span><span style="color: #008080;">not</span> <span style="color: #000000;">placingBlack</span><span style="color: #0000FF;">)</span> <span style="color: #008080;">and</span> <span style="color: #000000;">isAttacking</span><span style="color: #0000FF;">(</span><span style="color: #000000;">queen</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">pos</span><span style="color: #0000FF;">))</span> <span style="color: #008080;">then</span> ~~sequence queen := whitequeens[q]~~ if ~~queen~~<span style=="color: #000000;">pos</span> or<span ~~(placingBlack~~style="color: ~~and~~#0000FF;">=</span> ~~isAttacking(queen,~~<span ~~pos))~~style="color: ~~then~~#0000FF;">{}</span> <span ~~pos~~ style="color: {}#008080;">exit</span> <span style="color: #008080;">end</span> <span style="color: ~~exit~~#008080;">if</span> <span style="color: #008080;">end</span> <span style="color: #008080;">for</span> ~~end if~~ <span style="color: #008080;">if</span> <span style="color: #000000;">pos</span><span style="color: #0000FF;">!={}</span> <span style="color: #008080;">then</span> ~~end for~~ <span style="color: #008080;">for</span> <span style="color: #000000;">q</span><span style="color: #0000FF;">=</span><span style="color: #000000;">1</span> <span style="color: #008080;">to</span> <span style="color: #7060A8;">length</span><span style="color: #0000FF;">(</span><span style="color: #000000;">whitequeens</span><span style="color: #0000FF;">)</span> <span style="color: #008080;">do</span> ~~if pos!={} then~~ <span style="color: #004080;">sequence</span> <span style="color: #000000;">queen</span> <span style="color: #0000FF;">:=</span> <span style="color: #000000;">whitequeens</span><span style="color: #0000FF;">[</span><span style="color: #000000;">q</span><span style="color: #0000FF;">]</span> ~~if placingBlack then~~ <span style="color: #008080;">if</span> <span style="color: #000000;">queen</span> <span style="color: #0000FF;">==</span> <span style="color: #000000;">pos</span> <span style="color: #008080;">or</span> <span style="color: #0000FF;">(</span><span style="color: #000000;">placingBlack</span> <span style="color: #008080;">and</span> <span style="color: #000000;">isAttacking</span><span style="color: #0000FF;">(</span><span style="color: #000000;">queen</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">pos</span><span style="color: #0000FF;">))</span> <span style="color: #008080;">then</span> ~~blackqueens = append(blackqueens, pos)~~ <span style="color: #000000;">pos</span> <span style="color: #0000FF;">=</span> <span style="color: #0000FF;">{}</span> ~~placingBlack = false~~ ~~else~~ <span style="color: #008080;">exit</span> <span style="color: #008080;">end</span> ~~whitequeens~~<span style="color: ~~append(whitequeens, pos)~~#008080;">if</span> <span style="color: #008080;">end</span> <span style="color: #008080;">for</span> ~~if place(m-1, n, blackqueens, whitequeens) then return true end if~~ <span style="color: #008080;">if</span> <span style="color: #000000;">pos</span><span style="color: #0000FF;">!={}</span> <span style="color: #008080;">then</span> ~~blackqueens = blackqueens[1..$-1]~~ <span style="color: #008080;">if</span> <span style="color: #000000;">placingBlack</span> <span style="color: #008080;">then</span> ~~whitequeens = whitequeens[1..$-1]~~ <span style="color: #000000;">blackqueens</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">append</span><span style="color: #0000FF;">(</span><span style="color: #7060A8;">deep_copy</span><span style="color: #0000FF;">(</span><span style="color: #000000;">blackqueens</span><span style="color: #0000FF;">),</span> <span style="color: #000000;">pos</span><span style="color: #0000FF;">)</span> ~~placingBlack = true~~ <span style="color: #000000;">placingBlack</span> <span style="color: #0000FF;">=</span> <span style="color: #004600;">false</span> ~~end if~~ ~~end~~ if <span style="color: #008080;">else</span> <span style="color: #000000;">whitequeens</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">append</span><span style="color: #0000FF;">(</span><span style="color: #7060A8;">deep_copy</span><span style="color: #0000FF;">(</span><span style="color: #000000;">whitequeens</span><span style="color: #0000FF;">),</span> <span style="color: #000000;">pos</span><span style="color: #0000FF;">)</span> ~~end if~~ <span style="color: #008080;">if</span> <span style="color: #000000;">place</span><span style="color: #0000FF;">(</span><span style="color: #000000;">m</span><span style="color: #0000FF;">-</span><span style="color: #000000;">1</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">n</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">blackqueens</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">whitequeens</span><span style="color: #0000FF;">)</span> <span style="color: #008080;">then</span> <span style="color: #008080;">return</span> <span style="color: #004600;">true</span> <span style="color: #008080;">end</span> <span style="color: #008080;">if</span> ~~end for~~ <span style="color: #000000;">blackqueens</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">blackqueens</span><span style="color: #0000FF;">[</span><span style="color: #000000;">1</span><span style="color: #0000FF;">..$-</span><span style="color: #000000;">1</span><span style="color: #0000FF;">]</span> ~~end for~~ <span style="color: #000000;">whitequeens</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">whitequeens</span><span style="color: #0000FF;">[</span><span style="color: #000000;">1</span><span style="color: #0000FF;">..$-</span><span style="color: #000000;">1</span><span style="color: #0000FF;">]</span> ~~return false~~ <span style="color: #000000;">placingBlack</span> <span style="color: #0000FF;">=</span> <span style="color: #004600;">true</span> ~~end function~~ <span style="color: #008080;">end</span> <span style="color: #008080;">if</span> <span style="color: #008080;">end</span> <span style="color: #008080;">if</span> ~~for n=2 to 7 do~~ <span style="color: #008080;">end</span> <span style="color: #008080;">if</span> ~~for m=1 to n-(n<5) do~~ <span style="color: #008080;">end</span> <span style="color: #008080;">for</span> ~~if not place(m,n) then~~ <span style="color: #008080;">end</span> <span style="color: #008080;">for</span> ~~string no = sprintf("Cannot place %d+ queen armies on a %d-by-%d board",{m,n,n})~~ <span style="color: #008080;">return</span> <span style="color: #004600;">false</span> ~~if as_html then~~ <span style="color: #008080;">end</span> <span style="color: #008080;">function</span> ~~html &= sprintf("<b># %s</b><br><br>\n\n",{no})~~ ~~else~~ <span style="color: #008080;">for</span> <span style="color: #000000;">n</span><span style="color: #0000FF;">=</span><span style="color: #000000;">2</span> <span style="color: #008080;">to</span> <span style="color: #000000;">7</span> <span style="color: #008080;">do</span> ~~printf(1,"%s.\n", {no})~~ <span style="color: #008080;">for</span> <span style="color: #000000;">m</span><span style="color: #0000FF;">=</span><span style="color: #000000;">1</span> <span style="color: #008080;">to</span> <span style="color: #000000;">n</span><span style="color: #0000FF;">-(</span><span style="color: #000000;">n</span><span style="color: #0000FF;"><</span><span style="color: #000000;">5</span><span style="color: #0000FF;">)</span> <span style="color: #008080;">do</span> ~~end if~~ <span style="color: #008080;">if</span> <span style="color: #008080;">not</span> <span style="color: #000000;">place</span><span style="color: #0000FF;">(</span><span style="color: #000000;">m</span><span style="color: #0000FF;">,</span><span style="color: #000000;">n</span><span style="color: #0000FF;">)</span> <span style="color: #008080;">then</span> ~~end if~~ <span style="color: #004080;">string</span> <span style="color: #000000;">no</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">sprintf</span><span style="color: #0000FF;">(</span><span style="color: #008000;">"Cannot place %d+ queen armies on a %d-by-%d board"</span><span style="color: #0000FF;">,{</span><span style="color: #000000;">m</span><span style="color: #0000FF;">,</span><span style="color: #000000;">n</span><span style="color: #0000FF;">,</span><span style="color: #000000;">n</span><span style="color: #0000FF;">})</span> ~~end for~~ <span style="color: #008080;">if</span> <span style="color: #000000;">as_html</span> <span style="color: #008080;">then</span> ~~end for~~ <span style="color: #000000;">html</span> <span style="color: #0000FF;">&=</span> <span style="color: #7060A8;">sprintf</span><span style="color: #0000FF;">(</span><span style="color: #008000;">"<b># %s</b><br><br>\n\n"</span><span style="color: #0000FF;">,{</span><span style="color: #000000;">no</span><span style="color: #0000FF;">})</span> <span style="color: #008080;">else</span> ~~constant html_header = """~~ <span style="color: #7060A8;">printf</span><span style="color: #0000FF;">(</span><span style="color: #000000;">1</span><span style="color: #0000FF;">,</span><span style="color: #008000;">"%s.\n"</span><span style="color: #0000FF;">,</span> <span style="color: #0000FF;">{</span><span style="color: #000000;">no</span><span style="color: #0000FF;">})</span> ~~<!DOCTYPE html>~~ <span style="color: #008080;">end</span> <span style="color: #008080;">if</span> ~~<html lang="en">~~ <span style="color: #008080;">end</span> <span style="color: #008080;">if</span> ~~<head>~~ <span style="color: #008080;">end</span> <span style="color: #008080;">for</span> ~~<meta charset="utf-8" />~~ <span style="color: #008080;">end</span> <span style="color: #008080;">for</span> ~~<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />~~ ~~<title>Rosettacode Rank Languages by popularity</title>~~ <span style="color: #008080;">constant</span> <span style="color: #000000;">html_header</span> <span style="color: #0000FF;">=</span> <span style="color: #008000;">""" ~~</head>~~ <!DOCTYPE html> ~~<body>~~ <html lang="en"> ~~<h2>queen armies</h2>~~ <head> ~~""", -- or <div style="overflow:scroll; height:250px;">~~ <meta charset="utf-8" /> ~~html_footer = """~~ <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /> ~~</body>~~ <title>Queen Armies</title> ~~</html>~~ </head> ~~""" -- or </div>~~ <body> <h2>queen armies</h2> ~~if as_html then~~ """</span><span style="color: #0000FF;">,</span> <span style="color: #000080;font-style:italic;">-- or <div style="overflow:scroll; height:250px;"></span> ~~integer fn = open("queen_armies.html","w")~~ <span style="color: #000000;">html_footer</span> <span style="color: #0000FF;">=</span> <span style="color: #008000;">""" ~~puts(fn,html_header)~~ </body> ~~puts(fn,html)~~ </html> ~~puts(fn,html_footer)~~ """</span> <span style="color: #000080;font-style:italic;">-- or </div></span> ~~close(fn)~~ ~~printf(1,"See queen_armies.html\n")~~ <span style="color: #008080;">if</span> <span style="color: #000000;">as_html</span> <span style="color: #008080;">then</span> ~~end if~~ <span style="color: #008080;">if</span> <span style="color: #7060A8;">platform</span><span style="color: #0000FF;">()=</span><span style="color: #004600;">JS</span> <span style="color: #008080;">then</span> <span style="color: #7060A8;">puts</span><span style="color: #0000FF;">(</span><span style="color: #000000;">1</span><span style="color: #0000FF;">,</span><span style="color: #000000;">html</span><span style="color: #0000FF;">,</span><span style="color: #004600;">false</span><span style="color: #0000FF;">)</span> ~~?"done"~~ <span style="color: #008080;">else</span> ~~{} = wait_key()</lang>~~ <span style="color: #004080;">integer</span> <span style="color: #000000;">fn</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">open</span><span style="color: #0000FF;">(</span><span style="color: #008000;">"queen_armies.html"</span><span style="color: #0000FF;">,</span><span style="color: #008000;">"w"</span><span style="color: #0000FF;">)</span> <span style="color: #7060A8;">puts</span><span style="color: #0000FF;">(</span><span style="color: #000000;">fn</span><span style="color: #0000FF;">,</span><span style="color: #000000;">html_header</span><span style="color: #0000FF;">)</span> <span style="color: #7060A8;">puts</span><span style="color: #0000FF;">(</span><span style="color: #000000;">fn</span><span style="color: #0000FF;">,</span><span style="color: #000000;">html</span><span style="color: #0000FF;">)</span> <span style="color: #7060A8;">puts</span><span style="color: #0000FF;">(</span><span style="color: #000000;">fn</span><span style="color: #0000FF;">,</span><span style="color: #000000;">html_footer</span><span style="color: #0000FF;">)</span> <span style="color: #7060A8;">close</span><span style="color: #0000FF;">(</span><span style="color: #000000;">fn</span><span style="color: #0000FF;">)</span> <span style="color: #7060A8;">printf</span><span style="color: #0000FF;">(</span><span style="color: #000000;">1</span><span style="color: #0000FF;">,</span><span style="color: #008000;">"See queen_armies.html\n"</span><span style="color: #0000FF;">)</span> <span style="color: #008080;">end</span> <span style="color: #008080;">if</span> <span style="color: #008080;">end</span> <span style="color: #008080;">if</span> <span style="color: #0000FF;">?</span><span style="color: #008000;">"done"</span> <span style="color: #0000FF;">{}</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">wait_key</span><span style="color: #0000FF;">()</span> <!--</syntaxhighlight>--> {{out}} with as_html = false Line 5,634 ⟶ 6,038: =={{header\|Python}}== ===Python: Textual output=== <~~lang~~syntaxhighlight lang="python">from itertools import combinations, product, count from functools import lru_cache, reduce Line 5,707 ⟶ 6,111: m, n = 5, 7 ans = place(m, n) pboard(ans, n)</~~lang~~syntaxhighlight> {{out}} Line 5,807 ⟶ 6,211: ===Python: HTML output=== Uses the solver function <code>place</code> from the above textual output case. <~~lang~~syntaxhighlight lang="python">from peaceful_queen_armies_simpler import place from itertools import product, count Line 5,855 ⟶ 6,259: html += hboard(ans, n) with open('peaceful_queen_armies.htm', 'w') as f: f.write(html)</~~lang~~syntaxhighlight> {{out}} Line 6,449 ⟶ 6,853: (formerly Perl 6) {{trans\|Perl}} <syntaxhighlight lang="raku" ~~perl6~~line># recursively place the next queen sub place ($board, $n, $m, $empty-square) { my $cnt; Line 6,496 ⟶ 6,900: say $solution ?? "Solution to $m $n\n\n{S:g/(\N)/$0 / with $solution}" !! "No solution to $m $n";</~~lang~~syntaxhighlight> {{out}} <pre>W • ◦ • W Line 6,506 ⟶ 6,910: =={{header\|Ruby}}== {{trans\|Java}} <~~lang~~syntaxhighlight lang="ruby">class Position attr_reader :x, :y Line 6,625 ⟶ 7,029: print "No solution exists.\n\n" end end</~~lang~~syntaxhighlight> {{out}} <pre>1 black and 1 white queens on a 2 x 2 board: Line 6,795 ⟶ 7,199: {{libheader\|srfi-132}} <~~lang~~syntaxhighlight lang="scheme">;;; ;;; Solutions to the Peaceful Chess Queen Armies puzzle, in R7RS ;;; Scheme (using also SRFI-132). Line 7,024 ⟶ 7,428: (newline) (newline) (loop (+ next-solution-number 1))))))</~~lang~~syntaxhighlight> {{out}} Line 7,265 ⟶ 7,669: ===All non-equivalent solutions=== {{works with\|CHICKEN\|5.3.0}} <~~lang~~syntaxhighlight lang="scheme">;;; ;;; Solutions to the Peaceful Chess Queen Armies puzzle, in R7RS ;;; Scheme. This implementation returns only one of each equivalent Line 7,606 ⟶ 8,010: (newline) (newline) (loop (+ next-solution-number 1))))))</~~lang~~syntaxhighlight> {{out}} Line 7,654 ⟶ 8,058: {{trans\|Kotlin}} <~~lang~~syntaxhighlight lang="swift">enum Piece { case empty, black, white } Line 7,762 ⟶ 8,166: print("No solution") } }</~~lang~~syntaxhighlight> {{out}} Line 7,927 ⟶ 8,331: {{trans\|Kotlin}} {{libheader\|Wren-dynamic}} <~~lang~~syntaxhighlight ~~ecmascript~~lang="wren">import "./dynamic" for Enum, Tuple var Piece = Enum.create("Piece", ["empty", "black", "white"]) Line 8,019 ⟶ 8,423: System.print("No solution exists.\n") } }</~~lang~~syntaxhighlight> {{out}} Line 8,027 ⟶ 8,431: =={{header\|zkl}}== <~~lang~~syntaxhighlight lang="zkl">fcn isAttacked(q, x,y) // ( (r,c), x,y ) : is queen at r,c attacked by q@(x,y)? { r,c:=q; (r==x or c==y or r+c==x+y or r-c==x-y) } fcn isSafe(r,c,qs) // queen safe at (r,c)?, qs=( (r,c),(r,c)..) Line 8,059 ⟶ 8,463: z.text.pump(Void,T(Void.Read,N-1),"println"); } }</~~lang~~syntaxhighlight> <~~lang~~syntaxhighlight lang="zkl">peacefulQueens(); foreach n in ([4..10]){ peacefulQueens(n,n) }</~~lang~~syntaxhighlight> {{out}} <pre>