Leet Code:Single Number

题目描述

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?

解法

利用位异或操作：a&a=0; a&0=a，异或操作符合交换律和结合律（参见c/c++位操作简介--移位、位与、位或、异或）。

代码

class Solution {
public:
    int singleNumber(int A[], int n) {
        int res=A[0];
        for(int i=1;i<n;++i)
            res^=A[i];
        return res;
    }
};

参考

http://www.cnblogs.com/lailailai/p/3681697.html