66. Plus One

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.

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用一个数组表示一个数，然后对这个数加1，输出新的数组。很简单的题，注意一下进位即可。 完整代码如下：

class Solution {
public:
    vector<int> plusOne(vector<int>& digits)
    {
        vector<int> ans;
        int n = digits.size() – 1;
        digits[n]++;
        while (digits[n] >= 10 && n > 0) {
            digits[n] -= 10;
            digits[n – 1]++;
            n–;
        }
        if (n == 0 && digits[n] >= 10) {
            ans.push_back(1);
            digits[n] -= 10;
        }
        ans.insert(ans.end(), digits.begin(), digits.end());
        return ans;
    }
};

本代码提交AC，用时4MS。