[LeetCode] 136. Single Number

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

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

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