Algorithm Problem (Greedy Algorithm): Please provide more detail for learning purposes.

Give an example to show the greedy choice property and the optimal substructure in this problem

Design a greedy algorithm to solve this problem

Analyze the complexity of your algorithm.

Given a set S = {t, t2, ..., tn} of tasks, where t requires Pi units of processing time to finish once it has started. There is only one computer to run these tasks one at a time. The time before a task t starts is called its waiting time wi. The goal is come up with a schedule to minimize the overall waiting time , Wi