136. 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?

一个数组里每个数都出现两次，除了一个数只出现一次。想要找出这个只出现过一次的数，用异或^符可以轻松找到，代码如下：

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