Sicily-1438

一．      题意

买二送一。排序之后隔三求和，求折扣的最大值。

二．      代码

//
//  main.cpp
//  sicily-1438
//
//  Created by ashley on 14-11-7.
//  Copyright (c) 2014年 ashley. All rights reserved.
//

#include <iostream>
#include <algorithm>
using namespace std;

int prices[20000];

int main(int argc, const char * argv[])
{
    int cases , items;
    cin >> cases;
    while (cases--) {
        cin >> items;
        for (int i = 0; i < items; i++) {
            cin >> prices[i];
        }
        sort(prices, prices + items);
        int sum = 0;
        for (int i = items - 3; i >= 0; i = i - 3) {
            sum = sum + prices[i];
        }
        cout << sum << endl;
    }
    
    return 0;
}