查找数组中只出现一次的数（一）——Leetcode系列（十四）

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?

My Answer:

public class Solution {    public int singleNumber(int[] A) {        Set<Integer> set = new HashSet<Integer>();        int length = A.length;        for(int i = 0; i < length; i++){            if(set.contains(A[i])){                set.remove(new Integer(A[i]));            }else{                set.add(A[i]);            }        }        Iterator<Integer> ite = set.iterator();        return ite.next();    }}

题目来源：https://oj.leetcode.com/problems/single-number/