A server has n customers waiting to be served. The service time required by each customer is known in advance: it is t_i minutes for customer i. So if, for example, the customers are served in order of increasing t, then the ith customer has to wait sigma^i_j = 1 t_j minutes. We wish to minimize the total waiting time T = sigma^n_i = 1 (time spent waiting by customer i). (a) Give an efficient (greedy!) algorithm for computing the optimal order in which to process the customers. (b) Describe the greedy choice your algorithm makes and argue that it is correct