codeforces Round #263(div2) B解题报告

B. Appleman and Card Game

time limit per test
1 second

memory limit per test
256 megabytes

input
standard input

output
standard output

Appleman has n cards.
Each card has an uppercase letter written on it. Toastman must choose k cards
from Appleman's cards. Then Appleman should give Toastman some coins depending on the chosen cards. Formally, for each Toastman's card i you
should calculate how much Toastman's cards have the letter equal to letter on ith,
then sum up all these quantities, such a number of coins Appleman should give to Toastman.

Given the description of Appleman's cards. What is the maximum number of coins Toastman can get?

Input

The first line contains two integers n and k (1 ≤ k ≤ n ≤ 105).
The next line contains n uppercase
letters without spaces — thei-th
letter describes the i-th
card of the Appleman.

Output

Print a single integer – the answer to the problem.

Sample test(s)

input

15 10
DZFDFZDFDDDDDDF

output

82

input

6 4
YJSNPI

output

4

Note

In the first test example Toastman can choose nine cards with letter D and one additional card with any letter. For each card withD he
will get 9 coins and for the additional card he will get 1 coin.

题目大意：

给出n个字母，要求在里面选k个字母，每个字母都可以获得一定的金币，规则是：每个字母可以获得的金币 = 该字母在你选的字母串中的数量。

解法：

        每个字母获得的金币跟该字母在选取串中有直接的关系，所以，当然是选取越多的同个字母获得的金币越多，可以用贪心，按照字母的个数排序，优先选个数多的字母。

代码：

#include <cstdio>
#include <iostream>
#define LL long long

using namespace std;

int n;
LL a[30], ans, k;
bool use[30];

void init() {
scanf("%d%I64d\n", &n, &k);

for (int i = 1; i <= n; i++) {
char ch;

scanf("%c", &ch);
a[ch-'A'+1]++;
}
}

void solve() {
while (k) {
LL maxn = 0;
int maxx;

for (int i = 1; i <= 26; i++)
if (!use[i] && a[i] > maxn) {
maxn = a[i];
maxx = i;
}

use[maxx] = true;

if (k >= maxn) {
k -= maxn;
ans += maxn*maxn;
}
else {
ans += k*k;
k = 0;
}
}

cout << ans << endl;
}

int main() {
init();
solve();
}