Solve a Sudoku grid only using magic, recursion, and 140bytes of brute force.
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Sudoku Solver in 140bytes
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| function R | |
| ( | |
| a, // the array representing the sudoko grid | |
| // placeholder arguments | |
| i, // index of the last empty cell | |
| j, // index to check the candidates for the cell 'i' | |
| m, // candidate number for the the cell 'i' | |
| g // flag whether 'm' is a already used in the same row|col|node as 'i' | |
| ){ | |
| // phase 1: look for an empty cell | |
| for | |
| ( | |
| i=80; | |
| a[i]; // keep going if the cell isn't empty | |
| i--||+a // decrease the index and call 'a.toString()' if we went through the whole grid | |
| ); | |
| // phase 2: check all candidate numbers for the cell 'i' | |
| for | |
| ( | |
| m=10; | |
| g=a[i]=--m; // put the candidate in the cell 'i' already and set 'g' to something truthy | |
| // at the end of phase 2, the cell 'i' is reset to 0 for "higher" branches of the recursion | |
| g&&R(a) // recurse if 'm' isn't already used in the same row|col|node as 'i' | |
| ) | |
| // phase 3: check if the candidate number is used already | |
| for(j in a) // loop through the whole grid again | |
| g*= // turn 'g' falsy if | |
| a[j^i==j] // we are not on the cell 'i' | |
| ^m // and the cell 'j' is set to 'm' | |
| || // and we are in the same row|col|node as 'i' | |
| i/9^j/9&&i%9^j%9&&i/27^j/27|i%9/3^j%9/3 | |
| } |
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| function R(a,i,j,m,g){for(i=80;a[i];i--||+a);for(m=10;g=a[i]=--m;g&&R(a))for(j in a)g*=a[j^i==j]^m||i/9^j/9&&i%9^j%9&&i/27^j/27|i%9/3^j%9/3} |
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| DO WHAT THE FUCK YOU WANT TO PUBLIC LICENSE | |
| Version 2, December 2004 | |
| Copyright (C) 2011 Mathieu 'p01' Henri <http://www.p01.org/releases/> | |
| Everyone is permitted to copy and distribute verbatim or modified | |
| copies of this license document, and changing it is allowed as long | |
| as the name is changed. | |
| DO WHAT THE FUCK YOU WANT TO PUBLIC LICENSE | |
| TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION | |
| 0. You just DO WHAT THE FUCK YOU WANT TO. |
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| { | |
| "name": "sudokuSolver", | |
| "description": "Brute force sudoku solver.", | |
| "keywords": [ | |
| "sudoku", | |
| "solver", | |
| "recursive", | |
| "brute force" | |
| ] | |
| } |
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| <!doctype html> | |
| <title>Sudoku Solver in 140bytes</title> | |
| <div>Expected value: <b>4,2,8,1,5,9,6,7,3,1,9,6,3,7,4,8,2,5,3,7,5,8,6,2,9,4,1,9,8,1,4,2,3,5,6,7,5,6,4,7,1,8,3,9,2,7,3,2,5,9,6,1,8,4,2,4,3,6,8,1,7,5,9,6,1,7,9,4,5,2,3,8,8,5,9,2,3,7,4,1,6</b></div> | |
| <div>Actual value: <b id="ret"></b></div> | |
| <script> | |
| var testGrid = [0,0,0,1,5,0,0,7,0,1,0,6,0,0,0,8,2,0,3,0,0,8,6,0,0,4,0,9,0,0,4,0,0,5,6,7,0,0,4,7,0,8,3,0,0,7,3,2,0,0,6,0,0,4,0,4,0,0,8,1,0,0,9,0,1,7,0,0,0,2,0,8,0,5,0,0,3,7,0,0,0]; | |
| var myFunction = function R(a,i,j,m,g){for(i=80;a[i];i--||+a);for(m=10;g=a[i]=--m;g&&R(a))for(j in a)g*=a[j^i==j]^m||i/9^j/9&&i%9^j%9&&i/27^j/27|i%9/3^j%9/3}; | |
| (function(f) | |
| { | |
| var original=Array.prototype.toString; | |
| Array.prototype.toString=function sudokuToString() | |
| { | |
| if( (sudokuToString.caller||arguments.caller)==f ) | |
| document.getElementById( "ret" ).textContent= original.call(this); | |
| return original.call(this); | |
| } | |
| })( myFunction ); | |
| myFunction( testGrid ); | |
| </script> |
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