[LeetCode] Single Number

Problem:

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?

Solution:O(n)

public class Solution {

    public int singleNumber(int[] A) {
        int ret = 0;
        for(int a:A)
            ret^=a;
        return ret;    
    }
}