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?

利用异或运算的特点–相同为0，不同为1。

class Solution {public:    int singleNumber(vector<int>& nums) {        int n = nums.size();    int result=nums[0];            for(int i=1;i<n;i++)            {                result^= nums[i];             }            return result;    }};