single-number

题目描述

 

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 = result ^ A[i];
        }
        return result;
    }
}