[LeetCode] 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?

解答：

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

没什么可多说的，用到的知识点就是：a异或a = 0，a异或0 = a，异或满足交换律