136. Single Number

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

思路：所有數 ＸＯＲ起來，剩下的就是孤單的那一個了

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