66. Plus One

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.

翻译：给定一个用数组表示的非负整数，在此基础上加1

class Solution(object):
    def plusOne(self, digits):
        cnt = len(digits)
        if cnt == 0:
            digits.insert(0,1)
        last = cnt - 1
        flag = 0      
        while(last >= 0):
            plus = 0
            if (last == cnt-1 ):             
                plus = 1 
            number = digits[last] + plus + flag
            if number >= 10:                          
                digits[last]= number%10
                flag = number//10
            else:               
                digits[last] =  digits[last]+ plus+ flag
                flag = 0
            last-=1
        if(flag!=0):
            digits.insert(0,flag)
        return digits