leetcode_66. Plus One

题目：

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.

就是把这个加1了。简单

class Solution {
public:
    vector<int> plusOne(vector<int>& digits) {
        int i = digits.size()-1;
        for(i; i >=0; --i){
            if(digits[i] == 9){
                digits[i] = 0;
            }
            else{
                digits[i]++;
                return digits;
            }
        }
        if(i == -1){
            digits[0] = 1;
            digits.push_back(0);
        }
        
        return digits;
    }
};