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?

 

 

 

class Solution {public:    int singleNumber(int A[], int n) {        int rtv = 0;for(int i = 0; i < n; ++i)rtv ^= A[i];return rtv;    }};