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?

异或的经典题目。

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