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?

思路  A^B^A=B

class Solution {
public:
int singleNumber(vector<int>& nums) {

int res=nums[0];
for (int i = 1; i < nums.size(); i++)
res ^= nums[i];
return res;

}
};