Java Dequeue Hackerrank Solution For Explanation Watch Video: Sample Input 6 3 5 3 5 2 3 2 Sample Output 3 Code: import java.util.*; public class test { public static void main(String[] args) { Scanner in = new Scanner(System.in); Deque deque = new ArrayDeque<>(); int n = in.nextInt(); int m = in.nextInt(); int max = - 1 ; HashSet<Integer> hs = new HashSet<>(); for ( int i = 0 ; i < n; i++) { int input = in.nextInt(); deque.add(input); hs.add(input); if (deque.size() == m) { if (hs.size() > max) max = hs.size(); int first = ( int ) deque.remove(); if (!deque.contains(first)) hs.remove(first); } } System.out.println(max); }