The knapsack problem is a classic problem in computer science. You are given a knapsack and a collection of items of different weights and your job is to try to fit some combination of the items into the knapsack to obtain a target weight. All of the items do not have to fit in the knapsack, but the total weight cannot exceed the target weight. For example, suppose we want to fill the knapsack to a maximum weight of 30 pounds from a collection of seven items where the weights of the seven items are 2, 5, 6, 9, 12, 14, and 20. For a small number of items, it's rather easy to solve this problem. One such solution, for example, would be to include the items that have weights 2, 5, 9, and 14. But what if we had several thousand items of varying weights and need to fit them within a large knapsack? Design and implement a recursive algorithm for solving this problem.