Leetcode 136. 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?

s思路： 1. 这道题遇到过! 不用内存，那就是一直做xor运算，相同的数xor等于0，最后只剩下the single number. 2. 这道题就是利用两个数异或的性质，基本也就是一道数学题！

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