4 ms·

So is this the right answer?

• birken 10y ago
  Yes. Not too hard to confirm with a tiny little program: lockers = ['Closed'] * 101 for i in range(1, 101): for locker in range(i, 101, i): lockers[locker] = 'Open' if lockers[locker] == 'Closed' else 'Closed' print ([locker for locker, value in enumerate(lockers) if value == 'Open']) >>> [1, 4, 9, 16, 25, 36, 49, 64, 81, 100]