Contains Duplicate

Given an array of integers, find if the array contains any duplicates. Your function should return true if any value appears at least twice in the array, and it should return false if every element is distinct.

思路：利用HashSet集合元素的唯一性来确定int[]数组中是否用重复的元素出现。

代码如下：

public class Solution {    public boolean containsDuplicate(int[] nums) {        if(nums==null||nums.length==0) return false;        HashSet set = new HashSet();        int len = nums.length;                for(int i=0;i<len;i++){            if(set.contains(nums[i])){                return true;            }else{                set.add(nums[i]);            }        }                return false;    }}