[LeetCode] 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?

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