Problem: 2057B - Gorilla and the Exam
Language: java

Solution 1 (runtime: 562 ms):
// Gorilla and the exam

import java.util.*;

public class _2057B {
    public static void sovle(int k, int arr[]) {
        Arrays.sort(arr);
        List<Integer> cnt = new ArrayList<>();
        cnt.add(1);
        for (int i = 1; i < arr.length; i++) {
            if (arr[i] == arr[i - 1]) {
                cnt.set(cnt.size() - 1, cnt.get(cnt.size() - 1) + 1);
            } else {
                cnt.add(1);
            }
        }

        Collections.sort(cnt);
        int m = cnt.size();
        for (int i = 0; i < m - 1; i++) {
            if (cnt.get(i) > k) {
                System.out.println(m - i);
                return;
            }
            k -= cnt.get(i);
        }
        System.out.println(1);
    }

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int t = sc.nextInt();
        while (t > 0) {
            int n = sc.nextInt();
            int k = sc.nextInt();

            int arr[] = new int[n];

            for (int i = 0; i < n; i++) {
                arr[i] = sc.nextInt();
            }

            sovle(k, arr);

            t--;
        }
        sc.close();
    }
}

Solution 2 (runtime: 421 ms):

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.*;

public class B {
    static class FastReader {
        BufferedReader br;
        StringTokenizer st;

        public FastReader() {
            br = new BufferedReader(
                    new InputStreamReader(System.in));
        }

        String next() {
            while (st == null || !st.hasMoreElements()) {
                try {
                    st = new StringTokenizer(br.readLine());
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            return st.nextToken();
        }

        int nextInt() {
            return Integer.parseInt(next());
        }

        long nextLong() {
            return Long.parseLong(next());
        }

        double nextDouble() {
            return Double.parseDouble(next());
        }

        String nextLine() {
            String str = "";
            try {
                if (st.hasMoreTokens()) {
                    str = st.nextToken("\n");
                } else {
                    str = br.readLine();
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
            return str;
        }
    }
    public static void main(String[] args) {
        FastReader sc = new FastReader();
        int t = sc.nextInt();
        while (t != 0) {
            t--;
            int n = sc.nextInt();
            int k = sc.nextInt();
            long[] arr=new long[n];
            HashMap<Long,Long> map=new HashMap<>();
            for (int i = 0; i <n ; i++) {
                arr[i]= sc.nextLong();
                map.put(arr[i],map.getOrDefault(arr[i],(long)0 )+1);
            }
            ArrayList<Long> freq=new ArrayList<>();
            for(long key:map.keySet()){
                freq.add(map.get(key));
            }
            Collections.sort(freq);
            long ans=1;
            long rem=n-(freq.get(freq.size()-1)+k);
            if (rem>0) {
                for (int i = freq.size() - 2; i >= 0; i--) {
                     rem-=freq.get(i);
                     ++ans;
                     if (rem<=0){
                         break;
                     }
                }
            }
            System.out.println(ans);


        }
    }
}