*leetcode #136 in cpp

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?

Solution:

XOR can exclude same numbers. Since the arrays has only a single one. We can XOR all numbers, and all pairs would vanish.

Say 1 ^ 1 ^ 0 = 0. 

Code:

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