"""
Exercise 1: Plus One (LeetCode 66)

digits represents a non-negative integer, most significant digit first.
Add one and return the new digit list. Handle carries like [9,9] -> [1,0,0].
"""

def plus_one(digits):
    # TODO
    return digits


# --- self-check: do not modify below this line ---
a, b, c = plus_one([1, 2, 3]), plus_one([9, 9]), plus_one([0])
print(a, b, c)
print("PASS" if (a, b, c) == ([1, 2, 4], [1, 0, 0], [1]) else "FAIL")