Contains Duplicate II

Given an array of integers and an integer k, find out whether there are two distinct indices i and j in the array such that nums[i] = nums[j] 
and the difference between i and j is at most k.

Better idea is to maintain a hashset that contains at most k numbers

public class Solution {
    public boolean containsNearbyDuplicate(int[] nums, int k) {
        Set<Integer> set = new HashSet<Integer>();
        for(int i = 0; i < nums.length; i++){
            if(set.contains(nums[i])) return true;
            set.add(nums[i]);
            if(set.size()>k) set.remove(nums[i-k]);
        }
        return false;
    }
}