219. Contains Duplicate II (leetcode.com)

Solution.java

/*
Your runtime beats 98.60 % of java submissions.
Your memory usage beats 71.96 % of java submissions.
*/

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

        }
        return false;
    }
}