Leetcode--136.Single Number

题目

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?

思路

异或，不仅能处理两次的情况，只要出现偶数次，都可以清零。

代码

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