class Solution: def plusOne(self, digits: list[int]) -> list[int]: flag = 1 # x = digits[-1] + 1 # if x == 10: # flag = 1 # digits[-1] = 0 # else: # digits[-1] = x for i in range(len(digits) - 1, -1, -1): x = digits[i] + flag digits[i] = x if x == 10: flag = 1 digits[i] = 0 else: flag = 0 if digits[0] == 0: digits.insert(0, 1) return digits sol = Solution() print(sol.plusOne([1, 2, 3])) print(sol.plusOne([1, 2, 3, 4])) print(sol.plusOne([9]))