Single-number

题目描述

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?

代码：
public class Solution {
    public int singleNumber(int[] A) {
        int a = 0;
        for(int i = 0 ; i < A.length; i++)
        {
            a ^= A[i]; 
        }
        return a;
    }
}

首先定义一个数0，使这个数和数组中的元素进行亦或运算，最终得到答案.