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: Time Limit Exceeded)


import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;
import java.util.Set;
import java.util.stream.Collectors;

public class Main {

    public static void main(String[] args) {

        //		 solveA();
        //		 solveB();
        //		 solveC();
//		solveC2();
        solveD();
    }

    private static void solveA() {
        try (Scanner scanner = new Scanner(System.in)) {
            int lineAB = 0;
            int lineBC = 0;
            int lineCA = 0;

            lineAB = scanner.nextInt();
            lineBC = scanner.nextInt();
            lineCA = scanner.nextInt();

            int result = lineAB * lineBC / 2;
            System.out.println(result);

        }
    }

    private static void solveB() {

        try (Scanner scanner = new Scanner(System.in)) {

            int numS = 0;
            numS = scanner.nextInt();

            int wkResult = 0;

            List<Integer> wkList = new ArrayList<Integer>();
            int cnt = 0;
            while (true) {
                if (cnt != 0) {
                    /*
                     * isResultNum()でf(n)を計算する
                     */
                    wkResult = isResultNum(wkList.get(cnt - 1));
                    /*
                     * am=an(m>n)
                     * 現時点のcntの値より前に同じwkResultが出てきているのかをチェック
                     * 既におなじwkResultが既出ならcnt++してbreak（indexが0スタートなので1スタートに合わせる）
                     */
                    if (wkList.contains(wkResult)) {
                        cnt++;
                        break;
                    }
                    wkList.add(wkResult);
                } else {
                    wkResult = numS;
                    wkList.add(numS);
                }
                cnt++;
            }
            System.out.println(cnt);
        }
    }

    private static int isResultNum(int numS) {
        if (numS % 2 == 0) {
            return numS / 2;
        } else {
            return 3 * numS + 1;
        }
    }

    private static void solveC() {

        try (Scanner scanner = new Scanner(System.in)) {
            int numN = 0;
            numN = scanner.nextInt();
            int[] arrayH = new int[numN];
            for (int i = 0; i < arrayH.length; i++) {
                arrayH[i] = scanner.nextInt();
            }

            int cnt = 0;
            /*
             * 入力値がすべて0になるまで繰り返す
             */
            while (isNotExit(arrayH)) {
                cnt++;
                boolean notZeroCnt = false;
                /*
                 * 水やり作業
                 */
                for (int i = 0; i < arrayH.length; i++) {
                    /*
                     * 0に達したものはそれ以上水をやれないので、
                     * 0を見つけたら水やりの切れ目
                     */
                    if (arrayH[i] != 0) {
                        arrayH[i]--;
                        notZeroCnt = true;
                    } else {
                        /*
                         * 0の箇所があるので水やりの切れ目なのだが、
                         * まだ1度も水を挙げていない場合
                         * |0|0|1|0|
                         * ↑みたいな場合、1,2個目は無視しないといけない
                         * notZeroCntはそのために利用している。
                         * もっとうまいやり方。。。
                         */
                        if (notZeroCnt) {
                            break;
                        }
                    }

                }
            }
            System.out.println(cnt);
        }
    }

    /*
     * 高さ0より大きい入力値が存在するのかを確認する
     */
    private static boolean isNotExit(int[] arrayH) {
        for (int i = 0; i < arrayH.length; i++) {
            if (arrayH[i] != 0) {
                return true;
            }
        }
        return false;
    }

    private static void solveC2() {

        try (Scanner scanner = new Scanner(System.in)) {
            int numN = 0;
            numN = scanner.nextInt();
            int[] arrayH = new int[numN];
            for (int i = 0; i < arrayH.length; i++) {
                arrayH[i] = scanner.nextInt();
            }

            int cnt = 0;
            while (getFirst(arrayH) != 99999999) {
                boolean zeroCnt = false;
                for (int i = 0; i < arrayH.length; i++) {
                    if (arrayH[i] > 0) {
                        arrayH[i] = arrayH[i] - 1;
                        zeroCnt = true;
                    } else {
                        if (zeroCnt) {
                            break;
                        }
                    }
                }
                cnt++;
            }

            System.out.println(cnt);
        }
    }

    private static int getFirst(int[] arrayH) {

        for (int i = 0; i < arrayH.length; i++) {
            if (arrayH[i] > 0) {
                return i;
            }
        }
        return 99999999;
    }

    private static class Sushi {
        private long netaT;

        public long getNetaT() {
            return netaT;
        }

        public long getOishiD() {
            return oishiD;
        }

        private long oishiD;

        public Sushi(long netaT, long oishiD) {
            this.netaT = netaT;
            this.oishiD = oishiD;
        }
    }

    private static void solveD() {

        try (Scanner scanner = new Scanner(System.in)) {
            int n = scanner.nextInt();
            int k = scanner.nextInt();

            List<Sushi> wkList = new ArrayList<Sushi>();
            for (int i = 0; i < n; i++) {
                Sushi sushi = new Sushi(scanner.nextLong(), scanner.nextLong());
                wkList.add(sushi);
            }
            long res = DFS(wkList, n, 0, k, 0, new ArrayList<Long>());
            System.out.println(res);
        }
    }

    private static long DFS(List<Sushi> wkList, int n, int curr, int k, long total, List<Long> set) {
        if (k == 0) {
            long cnt = set.stream().collect(Collectors.toSet()).size();
            return cnt * cnt + total;
        }
        if (curr >= wkList.size()) {
            return 0;
        }
        long res = 0;
        long val = 0;
        val = DFS(wkList, n, curr + 1, k, total, set);
        res = Math.max(res, val);
        Sushi sushi = wkList.get(curr);
        set.add(sushi.getNetaT());
        val = DFS(wkList, n, curr + 1, k - 1, total + sushi.getOishiD(), set);
        set.remove(set.size() - 1);
        res = Math.max(res, val);
        return res;
    }
}