#include <iostream>
#include <vector>
#include <algorithm>

int max_saved(std::vector<int> prices, int k)
{
    int money_to_be_saved = 0;

    std::sort(prices.begin(), prices.end());
    std::reverse(prices.begin(), prices.end());

    int max_size = prices.size() - ( prices.size() % k );

    while( max_size < prices.size() )
        prices.pop_back();

    for(int i = 0; i < prices.size(); i += k)
        money_to_be_saved += *std::min_element( (prices.begin()+i), (prices.begin()+i+k) );

    return money_to_be_saved;
}

int main()
{
    int t, n, k, price;
    std::cin >> t;
    for(int i = 0; i < t; i++)
    {
        std::cin >> n >> k;
        std::vector<int> prices(n);
        for(int j = 0; j < n; j++)
        {
            std::cin>>price;
            prices[j] = price;
        }

        std::cout << max_saved(prices, k) << "\n";
    }
    return 0;
}