function solve()
{
$grid = makeEmptyGrid();
$list = [0, 1, 2, 3, 4, 5, 6, 7];
$tries = 0;
$solutions = 0;
foreach (permutations($list) as $permutation) {
$queens = [];
for ($i = 0; $i < 8; $i++) {
$queens[] = [$i, $permutation[$i]];
}
if (check($queens, $grid)) {
printSolution($queens);
$solutions++;
} else {
$tries++;
}
}
//print_r($solutions);
echo 'permutations tried: ' . $tries . '. solutions found: ' . $solutions;
}
public function test_check()
{
$grid = makeEmptyGrid();
$this->assertEquals(false, check([[0, 4], [1, 3], [2, 5], [3, 2], [4, 1], [5, 6], [6, 0], [7, 7]], $grid));
$this->assertEquals(true, check([[0, 2], [1, 7], [2, 3], [3, 6], [4, 0], [5, 5], [6, 1], [7, 4]], $grid));
}
