You need to ship n packages across the country using trucks. Each package i has a weight wi, and each truck can hold a total weight of M. You want to make the shipment using as few trucks as possible. More formally, given n packages with weights w1, w2,...,wn, and numbers M and K, is there a way to ship the packages using Ktrucks where the total weight carried by each truck is at most M? Prove that this problem is NP-hard. Then, find a greedy algorithm that uses at most twice as many trucks as optimal. Provide a proof.