Problem:
Score : 400 points

Problem Statement

There are N pieces of sushi. Each piece has two parameters: "kind of topping" t_i and "deliciousness" d_i.
You are choosing K among these N pieces to eat.
Your "satisfaction" here will be calculated as follows:

The satisfaction is the sum of the "base total deliciousness" and the "variety bonus".

The base total deliciousness is the sum of the deliciousness of the pieces you eat.

The variety bonus is x*x, where x is the number of different kinds of toppings of the pieces you eat.

You want to have as much satisfaction as possible.
Find this maximum satisfaction.

Constraints

1 \leq K \leq N \leq 10^5

1 \leq t_i \leq N

1 \leq d_i \leq 10^9

All values in input are integers.

Input

Input is given from Standard Input in the following format:

N K
t_1 d_1
t_2 d_2
.
.
.
t_N d_N

Output

Print the maximum satisfaction that you can obtain.

Sample Input 1

5 3
1 9
1 7
2 6
2 5
3 1

Sample Output 1

26

If you eat Sushi 1,2 and 3:

The base total deliciousness is 9+7+6=22.

The variety bonus is 2*2=4.

Thus, your satisfaction will be 26, which is optimal.

Sample Input 2

7 4
1 1
2 1
3 1
4 6
4 5
4 5
4 5

Sample Output 2

25

It is optimal to eat Sushi 1,2,3 and 4.

Sample Input 3

6 5
5 1000000000
2 990000000
3 980000000
6 970000000
6 960000000
4 950000000

Sample Output 3

4900000016

Note that the output may not fit into a 32-bit integer type.

Solution in Java8 (OpenJDK 1.8.0) (judge verdict: Runtime Error)


import java.io.Serializable;
import java.text.MessageFormat;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.HashSet;
import java.util.Objects;
import java.util.PriorityQueue;
import java.util.Scanner;

public class Main {

	/**
	 * problem solver
	 */
	public static class Problem {

		/**
		 * paramters
		 */
		private int n;
		private int k;
		private ArrayList<Integer> t;
		private ArrayList<Integer> d;

		/**
		 * constructor
		 */
		Problem() {
			t = new ArrayList<Integer>();
			d = new ArrayList<Integer>();
			n = 0;
			k = 0;
		}

		/**
		 * standard input
		 */
		void input() {
			Scanner sc = new Scanner(System.in);
			n = sc.nextInt();
			k = sc.nextInt();

			for (int i = 0; i < n; i++) {
				t.add(sc.nextInt());
				d.add(sc.nextInt());
			}
			sc.close();
		}

		/**
		 * Sushi
		 */
		public static class Sushi implements Comparable<Sushi>, Serializable {

			private static final long serialVersionUID = 7126883977005996870L;

			public int t;
			public int d;

			Sushi(int t, int d) {
				this.t = t;
				this.d = d;
			}

//            @Override
//            public int hashCode() {
//            	return Objects.hash(t,d);
//            }

			@Override
			public boolean equals(Object other) {
				if (other == this) {
					return true;
				}

				if (other instanceof Sushi) {
					Sushi that = (Sushi) other;
					return Objects.equals(that.d, this.d);
				}
				return false;
			}

			@Override
			public int compareTo(Sushi that) {
				Comparator<Integer> naturalOrder = Comparator.naturalOrder();
				return Objects.compare(this.d, that.d, naturalOrder);
			}

			@Override
			public String toString() {
				Integer[] params = { t, d };
				MessageFormat mf = new MessageFormat("({0},{1})");
				return mf.format(params);
			}
		}

		/**
		 * solver
		 */
		void solve() {
			PriorityQueue<Sushi> addCandidates = new PriorityQueue<>(Collections.reverseOrder());
			PriorityQueue<Sushi> delCandidates = new PriorityQueue<>();
			HashSet<Integer> hset = new HashSet<>();

			long a1 = 0; // sum of deliciousness
			long a2 = 0; // # kinds of toppings
			long ans = 0; // a1 + a2 * a2

			for (int i = 0; i < n; i++) {
				Sushi s = new Sushi(t.get(i), d.get(i));
				addCandidates.add(s);
			}

			for (int i = 0; i < k; i++) {
				Sushi s = addCandidates.poll();

				a1 += s.d;

				if (hset.contains(s.t)) {
					delCandidates.add(s);
				} else {
					a2++;
					hset.add(s.t);
				}
			}

			ans = a1 + a2 * a2;

			while (!addCandidates.isEmpty() || !delCandidates.isEmpty()) {

				long _ans = ans;

				Sushi deleted = delCandidates.poll();

				Sushi added = null;

				while (!addCandidates.isEmpty()) {
					Sushi s = addCandidates.peek();

					if (hset.contains(s.t)) {
						addCandidates.poll();
					} else {
						hset.add(s.t);
						added = s;
						break;
					}
				}

				if (added != null) {
					a1 += -deleted.d + added.d;
					a2++;
					_ans = a1 + a2 * a2;
					ans = Math.max(ans, _ans);
				}
			}

			System.out.println(ans);

		}

	}

	public static void main(String args[]) {

		Problem p = new Problem();

		p.input();

		p.solve();
	}
}