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

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