Кодовый замок

class Lock
{
    public $n;
    public $attempts = 1;
    public $combinations = [];

    function __construct($n = 1) {
        $this->n = $n;

        $c = 0;

        for($row = 0; $row < 2**$n; $row++) {
            $r = [];
            $sum = 0;
            for ($col = 0; $col < $n; $col++) {
                $r[$col] = ($c >> ($col)) % 2;
                $sum += $r[$col];
            }

            $this->combinations[$sum][] = $r;
            $c++;
        }

        $max = 0;
        for($row = 0; $row < $n; $row++) {
            $len = count($this->combinations[$row]);
            if($len > $max)
                $max = $len;
        }

        $this->attempts = $max;
    }
}


......

    for ($n = 2; $n <= 10; $n++){
        $lock = new Lock($n);
        dump($lock);
    };