Leetcode: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?

分析：所有元素异或，最终结果就是出现一次的数本文地址

 1 class Solution {
 2 public:
 3     int singleNumber(int A[], int n) {
 4         // Note: The Solution object is instantiated only once and is reused by each test case.
 5         int res = 0;
 6         for(int i = 0; i < n; i++)
 7             res = res^A[i];
 8         return res;
 9     }
10 };