4)Given a set of integers, Display the non-empty subsets whose sum is zero. For example, given the set { −7, −3, −2, 5, 8}, the answer is the subset { −3, −2, 5} which sums to zero. This is the special case of knapsack problem and hence it is NP- Complete so i said we cannot find the solution in polynomial time.We consider all the subsets with k elements. Then check how many of these sets have a sum of 0. This is an exponential time algorithm