def plusOne(self, digits: List[int]) -> List[int]:
        for i in range(len(digits)-1, -1, -1): #倒叙遍历
            digits[i]+=1
            digits[i] = digits[i]%10
            if digits[i] != 0:
                return digits
        res = [0]*(len(digits)+1)
        res[0] = 1
        return res
        