Leetcode 136 Single Number

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?
找出唯一一个只出现一次的数字。
学异或时的经典题型！

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