66. Plus One

题目描述：

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

You may assume the integer do not contain any leading zero, except the number 0 itself.

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

我的思路：

        没大看懂是什么意思。。用一个数组存储一个非负整数，把他加一。。。大数加法。

        保存进位，如果最后一位也有进位的话在前面添1。

我的代码：

class Solution:
    def plusOne(self, digits):
        """
        :type digits: List[int]
        :rtype: List[int]
        """
        n, p = len(digits) - 1, 1
        while n >= 0:
            p, digits[n] = divmod(digits[n] + p, 10)
            n -= 1

        if digits[0] == 0:
            digits.insert(0, 1)

        return digits

Discuss：

def plusOne(digits):
    num = 0
    for i in range(len(digits)):
    	num += digits[i] * pow(10, (len(digits)-1-i))
    return [int(i) for i in str(num+1)]

学到：