Advent of code 2021/17

Ajax Direct

function simulate($vx, $vy, $t) {
    [$x, $y] = [0, 0];
    $maxy = 0;
    $my = min($t[2], $t[3]);

    while (true) {
        $x += $vx;
        $y += $vy;
        $maxy = max($maxy, $y);

        if ($x >= $t[0] && $x <= $t[1] && $y >= $t[2] && $y <= $t[3]) {
            return [$maxy, $vx, $vy];
        }

        if ($x > $t[1] || $y < $my) {
            return false;
        }

        $vx =  max(0, $vx - 1);
        $vy -= 1;
    }
}

$t = $input->numbers();

$ok = [];
foreach (range(0, $t[1]) as $vx) {
    foreach (range ($t[2], $t[1]) as $vy) {
        if ($maxy = simulate($vx, $vy, $t)) {
            $ok[] = $maxy[0];
        }
    }
}

$solution_1 = max($ok);
$solution_2 = count($ok);