HDU 5999

题意：

        T 组数据 ， 每组数据 N 个数据 ， 每个 数在1000以内。

        买 N 个东西，买 2 送一 ，问买所有东西的最小话费。

思路：

        排个序就行

代码：

#include <iostream>#include <cstdio>#include <algorithm>using namespace std;int main(){    int T,n,ans,a[(int)1e5+100];    while(scanf("%d",&T)!=-1){        for(int ppp=1;ppp<=T;ppp++){            ans=0;            scanf("%d",&n);            for(int i=1;i<=n;i++){                scanf("%d",&a[i]);                ans+=a[i];            }            sort(a+1,a+n+1,greater<int>());            for(int i=3;i<=n;i+=3) ans-=a[i];            printf("Case #%d: %d\n",ppp,ans);        }    }}

Panda and his friends were hiking in the forest. They came across a coffee bar inside a giant tree trunk. 
Panda decided to treat everyone a cup of coffee and have some rest. Mr. Buck, the bartender greeted Panda and his animal friends with his antler. He proudly told them that his coffee is the best in the forest and this bar is a Michelin-starred bar, thats why the bar is called Starred Bucks. 
There was a campaign running at the coffee bar: for every 3 cups of coffee, the cheapest one is FREE. After asking all his friends for their flavors, Panda wondered how much he need to pay. 

Input

The first line of the input gives the number of test cases, T. 
T test cases follow. Each test case consists of two lines. The first line contains one integer N, the number of cups to be bought. 
The second line contains N integers p1,p2,・・・,pNp1,p2,・・・,pNrepresenting the prices of each cup of coffee. 

Output

For each test case, output one line containing “Case #x: y”, where x is the test case number (starting from 1) and y is the least amount of money Panda need to pay. 

limits

∙∙ 1 ≤ T ≤ 100. 
∙∙ 1 ≤ N ≤ 105105. 
∙∙ 1 ≤ pi ≤ 1000. 

Sample Input

231 2 3510 20 30 20 20

Sample Output

Case #1: 5Case #2: 80