Knapsack algorithm problem: Consider the following variation of
the Knapsack problem. There are n types of items, let call them
1,2,3,4,...,n. There are exactly c_i copies of item i, and each
such copy has value v_i and weight w_i. As before, the knapsack
capacity is W, and the other constraint is that you can only take
at most c_i copies of item i ( since no more are available). Show
how to compute the optimal value that can be achieved...