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;
    }
};