Locker problem

# lockers = [1] * 1001

# for student in range(1, 1001, 1):

   

#     # on second students

#     if student % 2 == 0:

#         for i in range(2, 1001, 2):

#             lockers[i] = 1

#     # on third student

#     elif student % 3 == 0:

#         for i in range(3, 1001, 3):

#             lockers[i] = not lockers[i]

#     else:

#         for i in range(1, 1001, 1):

#             lockers[i] = 0

# print(lockers.count(1))

# theres a bug in this code: person 4 will actually be counted as second person instead of first

# and i misunderstaod the problem, oops..

# ---------------------------------------------------------------------------------------

lockers = [1] * 1001

for student in range(1, 1001):

    for locker in range(student, 1001, student):

        # Student 1 -> change locker 1, 2, 3, 4, 5, ...

        # Student 2 -> change locker 2, 4, 6, 8, ...

        # Student 3 -> change locker 3, 6, 9, 12, ...

        # Student 4 -> change locker 4, 8, 12, 16, ...

        # Student 5 -> change locker 5, 10, 15, 20, ...

        lockers[locker] = not lockers[locker]   # each student's action is just changing the state of the locker

                                                # so doing not lockers[locker] is fine

print(lockers.count(1) - 1)

# this version works!