Leetcode 136 Single Number

Given a non-empty 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?

Example 1:

Input: [2,2,1]
Output: 1

Example 2:

Input: [4,1,2,1,2]
Output: 4

异或

这题和leetcode 268一样. 利用一个数异或某个数两次, 等于没异或.

class Solution {
    public int singleNumber(int[] nums) {
        int a = 0;
        for(int i : nums)
            a ^= i;
        return a;
    }
}