Basket Full of Balls - JAVA

// Author : Saurav Kalsoor
// Basket Full of Balls - JAVA


import java.util.*;

public class Test {

    static Scanner sc = new Scanner(System.in);

    public static void main(String[] args) {
        int n = sc.nextInt();
        int k = sc.nextInt();

        ArrayList<Integer> arr = new ArrayList<>();
        for(int i=0; i < n ;i++){
            arr.add(sc.nextInt());
        }

        System.out.println(bucketFullOfBalls(n, k, arr));
    }

    public static int bucketFullOfBalls(int n, int k, ArrayList<Integer> arr){
        HashMap<Integer, Integer> count = new HashMap<>();
        for(int x : arr){
            count.put(x, count.getOrDefault(x, 0) + 1);
        }

        ArrayList<Integer> temp = new ArrayList<>();
        for(Map.Entry<Integer, Integer> m : count.entrySet()){
            if(m.getValue() >= k){
                temp.add(m.getKey());
            }
        }

        int m = temp.size();
        if(m == 0){
            return -1;
        }



        int l = temp.get(0), r = l, i = 1;
        while(i < m){
            int j = i - 1;
            while(i < m && temp.get(i) == temp.get(i-1) + 1){
                i++;
            }
            i--;

            if(temp.get(i) - temp.get(j) > r - l){
                l = temp.get(j);
                r = temp.get(i);
            }

            i+=2;
        }

        return r - l;
    }
}