Advent of code 2023/11

Ajax Direct

function solve($galaxies, $empty_x, $empty_y, $expansion) {
    foreach ($galaxies as [&$x, &$y]) {
        $x += $empty_x->filter(fn ($ex) => $ex < $x)->count() * ($expansion - 1);
        $y += $empty_y->filter(fn ($ey) => $ey < $y)->count() * ($expansion - 1);
    }

    $total = 0;
    for ($i = 0; $i < count($galaxies) - 1; $i++)
        for ($j = $i + 1; $j < count($galaxies); $j++)
            $total += manhattan($galaxies[$i], $galaxies[$j]);
    return $total;
}

$grid = grid($input);
$empty_y = $grid->rows()->filter(fn ($l) => !$l->hasValue("#"))->keys();
$empty_x = $grid->columns()->filter(fn ($l) => !$l->hasValue("#"))->keys();
$galaxies = $grid->searchAll("#");

$solution_1 = solve($galaxies, $empty_x, $empty_y, 2);
$solution_2 = solve($galaxies, $empty_x, $empty_y, 1000000);