[leetcode]Plus One @ Python

原题地址：https://oj.leetcode.com/problems/plus-one/

题意：

Given a non-negative number represented as an array of digits, plus one to the number.

The digits are stored such that the most significant digit is at the head of the list.

解题思路：设置一个进位标志CarryFlag就可以了。For example: 999 + 1 = 1000

代码：

class Solution:
    # @param digits, a list of integer digits
    # @return a list of integer digits
    def plusOne(self, digits):
        carryFlag = 1
        for i in reversed(range(len(digits))):
            if digits[i] + carryFlag == 10:
                digits[i] = 0
                carryFlag = 1
            else:
                digits[i] += carryFlag
                carryFlag = 0
        
        if carryFlag == 1:
            digits.insert(0, 1)
        return digits