# 66. Plus One

**<font color=red>难度:Easy<font>**

## 刷题内容

> 原题连接

* https://leetcode.com/problems/plus-one/

> 内容描述

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

The digits are stored such that the most significant digit is at the head of the list, and each element in the array contain a single digit.

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

Example 1:

Input: [1,2,3]
Output: [1,2,4]
Explanation: The array represents the integer 123.
Example 2:

Input: [4,3,2,1]
Output: [4,3,2,2]
Explanation: The array represents the integer 4321.

```


> 思路1

******- 时间复杂度: O(n)******- 空间复杂度: O(1)******

将字符转成数字即可，不过这里要注意有可能会进一

```cpp
class Solution {
public:
    vector<int> plusOne(vector<int>& digits) {
        int i = digits.size() - 1;
        while((i >= 0) &&  (digits[i] == 9))
        {
            digits[i] = 0;
            --i;
        }
        if(i < 0)
            digits.insert(digits.begin(),1);
        else
            ++digits[i];
        return digits;
    }
};
```