sicily 1438 Shopaholic

从大到小排好序直接把每三个的最后一个加起来...

#include <bits/stdc++.h>

using namespace std;

int a[20005];

bool cmp(int a, int b)
{
    return a > b;
}

int main()
{
    int t;
    cin >> t;
    while(t--)
    {
        int n;
        cin >> n;
        for(int i=0; i<n; i++)
            cin >> a[i];
        sort(a, a+n, cmp);
        int sum=0;
        for(int i=2; i<n; i+=3)
            sum += a[i];
        cout << sum << endl;
    }
    return 0;
}