20160307 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?

思路：

采用XOR思想，A XOR A = 0

代码：

public class Solution {    public int singleNumber(int[] nums) {        int sum = 0;        for(int i = 0; i < nums.length; i++)        {            sum = sum ^ nums[i];        }        return sum;    }}