using System;

using System.Linq;

using System.Collections.Generic;

​

// Get as many values from Value before it it the target and it must be exsact to target value in sum.

public class Program

{

    static List<int> Values = new List<int>{0,0,0,1,1,2,3,4,4,5,6,9,10,12,15,20};

    public static void Main()

    {

        Console.WriteLine(GetValues(Values, 10).Count);

        Console.WriteLine(GetValues(Values, 5).Count);

    }

    static List<int> GetValues(List<int> values, int target)

    {

        List<int> total = new List<int>();

        foreach(int val in values.Where(value => value <= target).OrderByDescending(value => value))

        {

            total.Add(val);

            if(total.Sum() == target) return total;

            if(total.Sum() > target)

            {

                // Overflow, we need to remove an item to match better

            }

        }

        return new List<int>();

    }

}