def redistribute(banks):
    index, count = max(enumerate(banks), key=lambda iv: (iv[1], -iv[0]))
    banks[index] = 0
    for i in range(count):
        target = (i + index + 1) % len(banks)
        banks[target] += 1


test = [0, 2, 7, 0]
redistribute(test)
assert test == [2, 4, 1, 2]
redistribute(test)
assert test == [3, 1, 2, 3]
redistribute(test)
assert test == [0, 2, 3, 4]
redistribute(test)
assert test == [1, 3, 4, 1]
redistribute(test)
assert test == [2, 4, 1, 2]


def find_circle(banks):
    seen = set()
    while tuple(banks) not in seen:
        seen.add(tuple(banks))
        redistribute(banks)
    return len(seen)


assert find_circle([0, 2, 7, 0]) == 5

print("Part 1:", find_circle(banks))

# starting from the last test banks setting, length of the loop
assert find_circle(test) == 4

# starting from the last banks state, length of the loop
print("Part 2:", find_circle(banks))