Single Number

Q:
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?

Using bitwise XOR to find the single number, only the same number can unmark it.

Solution:

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