Minimize Unique - JAVA

// Author : Saurav Kalsoor
// Minimize Unique Numbers - 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(minimizeUnique(arr, k));
    }

    public static int minimizeUnique(ArrayList<Integer> arr, int k){
        HashMap<Integer, Integer> count = new HashMap<>();

        for(int num : arr){
            count.put(num, count.getOrDefault(num, 0) + 1);
        }

        Set<MyPair> st = new TreeSet<>(new Comparator<MyPair>() {
            @Override
            public int compare(MyPair a, MyPair b) {
                if(a.second == b.second)
                    return a.first - b.first;
                return a.second - b.second;
            }
        });

        for(Map.Entry<Integer, Integer> x : count.entrySet()){
            st.add(new MyPair(x.getKey(), x.getValue()) );
        }

        int res = st.size();

        for(MyPair x : st){
            if(k >= x.second){
                res--;
                k -= x.second;
            }else{
                break;
            }
        }

        return res;
    }

}

class MyPair{
    public int first, second;

    public MyPair(int first, int second){
        this.first = first;
        this.second = second;
    }
}