Single Number

今天讲一道已成烂柿子的题。如下：

Given an array of integers, every element appears twice except for one. Find that single one.

Note:

Your algorithm should have a linear runtime complexity. Could you implement it without using extra memory?

算法大家都知道，就是取个异或。

class Solution {
public:
    int singleNumber(vector<int>& nums) {
        int res = 0;
        for(int i = 0; i < nums.size(); i++) {
            res ^= nums[i];
        }
        return res;
    }
};