Contains Duplicate

Contains Duplicate

问题：

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：

　　hash

我的代码：

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