### CSC 421: Algorithm Design & Analysis Spring 2018 HW4: Greedy Scheduling

Consider the challenge of constructing a daily schedule given a (potentially large) set of event options. For example, a student planning his or her day might choose from the following possible events:

StartEndEvent
0:00 7:30 Sleep
0:00 10:20 Sleep in
7:45 8:00 Shower
8:00 8:45 Breakfast with friends
8:50 10:30 Study for class
11:00 12:15 *CSC 581
12:30 13:45 Lunch
12:30 13:30 Exercise
13:30 13:50 Power nap
14:00 15:15 *CSC 421
15:15 15:25 Call parents

In general, two events are in conflict if one is entirely contained with the other (e.g., Exercise is contained within Lunch) or the end of the earlier event is after the start of the later event (e.g., Study for class overlaps with Sleep in). Events that are required, i.e., must be included in any schedule, are preceded with an asterisk. You may assume that required events cannot be in conflict with each other.

You are to implement four different greedy approaches for constructing a schedule:

• Shortest event first: Repeatedly select the shortest event that does not conflict with previously selected events. For example, after adding the required events (CSC 581 and CSC 421) from above, the first optional event to be selected would be Call parents since it only takes 10 minutes. Next would be Shower (15 minutes), Power nap (20 minutes) and YouTube (30 minutes). The next shortest event, Breakfast with friends (45 minutes), cannot be selected since it conflicts with YouTube, so Exercise (1 hour) is selected next.
• Longest event first: Repeatedly select the longest event that does not conflict with previously selected events. For example, after adding the required events (CSC 581 and CSC 421) from above, the first optional event to be selected would be Sleep in since it is 10 hours and 20 minutes long. The next longest events, Sleep (7 hours 30 minutes) and Study for class (1 hour 40 minutes), cannot be selected since they conflict with Sleep in, so Lunch (1 hour 15 minutes) is selected next.
• Earliest start-time first: Repeatedly select the non-conflicting event that has the earliest start-time. For example, after adding the required events (CSC 581 and CSC 421) from above, the first event to be selected would be either Sleep or Sleep in since they both start at 0:00 (ties can be broken arbitrarily). Suppose, Sleep was selected. It would then be followed by Shower (7:45) and Breakfast with friends (8:00).
• Earliest end-time first: Repeatedly select the non-conflicting event that has the earliest end-time. For example, after adding the required events (CSC 581 and CSC 421) from above, the first event to be selected would be Sleep since it ends at 7:30. It would then be followed by Shower (8:00) and YouTube (8:40).

Your program should read in a text file, with each line specifying the start and end times (in military notation) and a description of a single event. For example, see events.txt. Your program should display the four schedules generated using the above greedy strategies. Each schedule should list the selected events in chronological order (one event per line) and should clearly identify the approach used. Asterisks should NOT appear when displaying required events and times should be properly aligned. For example:

Shortest event first: --------------------- 0:00 7:30 Sleep 7:45 8:00 Shower 8:10 8:40 YouTube ... Longest event first: -------------------- 0:00 10:20 Sleep in 11:00 12:15 CSC 581 12:30 13:45 Lunch ... Earlist start-time first: ------------------------- 0:00 7:30 Sleep 7:45 8:00 Shower 8:00 8:45 Breakfast with friends ... Earlist end-time first: ----------------------- 0:00 7:30 Sleep 7:45 8:00 Shower 8:10 8:40 YouTube ...

In completing this assignment, you are free to use classes in the official Java libraries, but you may not utilize any other classes that you did not write yourself. You should follow good object-oriented practices in completing the program, defining highly-cohesive and loosely-coupled classes as needed. Likewise, avoid duplicate and redundant code wherever possible.