The main danger with using the mod operator is that you can get an off-by-one if you aren't in the habit of using it and forget the exact definition. If that's

The main danger with using the mod operator is that you can get an off-by-one if you aren't in the habit of using it and forget the exact definition. If that's in doubt, rolling your own thing with a division or a while/if makes for a stronger guarantee of success on the first try. In an interview you could explain your reasoning for such a detour as well, which might work out better than just "knowing the answer."