Solver for c't Cover Puzzle at www.ct.de/600

solver.js

// solver.js: Solve the puzzle at www.ct.de/600
// by Harald Bögeholz (c't) & Alexander Jost (info@alexanderjost.com)
(function () {
"use strict";

var solve600 = 1; // 0: solve for c't 1 / 1: solve for c't 600

var numCols = 0;
while($('#pos0-' + numCols + '-0').length > 0)
    numCols++;
var numRows = 0;
while($('#pos0-0-' + numRows).length > 0)
    numRows++;

var matrix = [];
for (var r1 = 0; r1 < numRows; ++r1)
    for (var c1 = 0; c1 < numCols; ++c1) {
        var v = [];
        for (var r2 = 0; r2 < numRows; ++r2)
            for (var c2 = 0; c2 < numCols; ++c2)
                v.push(Math.abs(r1-r2)+Math.abs(c1-c2) <= 1 ? 1 : 0);
        var cp = $('#pos0-' + c1 + '-' + r1);
        v.push(solve600 ^ (cp.hasClass('state1') ? 1 : 0));
        matrix.push(v);
    }

for (var c=0; c < numCols*numRows; ++c) {
    var r = c;
    while (!matrix[r][c])
        ++r;
    if (r != c) {
        var tmp = matrix[c];
        matrix[c] = matrix[r];
        matrix[r] = tmp;
    }
    for (r=0; r < numCols*numRows; ++r)
        if (r != c && matrix[r][c])
            for (i=0; i < numCols*numRows+1; ++i)
                matrix[r][i] ^= matrix[c][i];
}

var i=0;
for (var r=0; r < numRows; ++r)
    for (var c=0; c < numCols; ++c)
        if (matrix[i++][numRows*numCols])
            $('#cell-' + c + '-' + r)[0].click();
})();