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.
解题：贪心。
1 #include <iostream> 2 #include <cstdio> 3 #include <cstring> 4 #include <cmath> 5 #include <algorithm> 6 #include <climits> 7 #include <vector> 8 #include <queue> 9 #include <cstdlib> 10 #include <string> 11 #include <set> 12 #include <stack> 13 #define LL long long 14 #define pii pair<int,int> 15 #define INF 0x3f3f3f3f 16 using namespace std; 17 int letter[27]; 18 char str[100100]; 19 bool cmp(const int &x,const int &y){ 20 return x > y; 21 } 22 int main() { 23 int n,k; 24 LL ans; 25 while(~scanf("%d %d",&n,&k)){ 26 memset(letter,0,sizeof(letter)); 27 scanf("%s",str); 28 for(int i = 0; str[i]; i++) letter[str[i]-‘A‘]++; 29 sort(letter,letter+26,cmp); 30 for(int i = ans = 0; k && i < 26; i++){ 31 ans += 1LL*min(k,letter[i])*min(k,letter[i]); 32 k -= min(k,letter[i]); 33 } 34 cout<<ans<<endl; 35 } 36 return 0; 37 }
Codeforces 263B. Appleman and Card Game
原文：http://www.cnblogs.com/crackpotisback/p/3938682.html
