מעקב רקורסיה ומחסנית

1public static boolean secret1 (int num, int digit)
2{
3    if (num < 10)
4        return (num % 2 == digit % 2);
5    if (num % 2 != digit % 2)
6        return false;
7    return secret1 (num / 10, digit);
8}
9
10public static boolean secret2 (Stack <Integer> s)
11{
12    boolean ok;
13    int x;
14    if (s.isEmpty())
15        ok = true;
16    else
17    {
18        x = s.pop();
19        if (! (secret1 (x, x % 10)))
20            ok = false;
21        else
22            ok = secret2 (s);
23    }
24    return ok;
25}