题目链接:http://codeforces.com/problemset/problem/462/B
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?
The first line contains two integers n and k (1 ≤ k ≤ n ≤ 105).
The next line contains n uppercase letters without spaces — the i-th
letter describes the i-th card of the Appleman.
Print a single integer – the answer to the problem.
15 10
DZFDFZDFDDDDDDF
82
6 4
YJSNPI
4
In the first test example Toastman can choose nine cards with letter D and one additional card with any letter. For each card with D he
will get 9 coins and for the additional card he will get 1 coin.
题意：
共同拥有N张牌，从中选出K张，得分为每次选出牌的面值与选该牌的数量。求最大得分。
PS:
贪心。从牌数多的面值開始选。
代码例如以下：
#include <cstdio>
#include <cstring>
#include <algorithm>
using namespace std;
typedef __int64 LL;
int main()
{
LL n, k;
LL a[47];
char s[100017];
while(~scanf("%I64d%I64d",&n,&k))
{
memset(a,0,sizeof(a));
scanf("%s",s);
for(int i = 0; i < n; i++)
{
a[s[i]-'A']++;
}
sort(a,a+26);
LL ans = 0;
for(int i = 25; i >= 0; i--)
{
if(k >= a[i])
{
ans+=a[i]*a[i];
k -= a[i];
if(k == 0)
break;
}
else
{
ans+=k*k;
break;
}
}
printf("%I64d\n",ans);
}
return 0;
}