CSC 151.03, Class 39: Merge Sort
Overview
- Preliminaries
- Notes and news
- Upcoming work
- Extra credit
- Exam stuff
- Questions
- Quiz
- Lab
- Debrief
News / Etc.
- I hope to have tentative project grades to you by Monday (ignoring the presentation component).
- We will discuss the form of the final next Monday.
- I plan to have all your grades to you Monday of finals week.
Upcoming work
- Writeup for class 38 due Friday at 10:30 p.m.
- Exercise 5
- To: csc151-03-grader@grinnell.edu
- Subject: CSC 151.03 Writeup 38 (YOUR NAMES)
- Due to a power failure, there is no writeup for class 39.
- If there were, it would have been Exercise 4f, 4g, 4h.
- Exam 4
- Prologue due Friday
- Exam due Tuesday
- Cover sheets due Wednesday
- Epilogues due Wednesday.
- No more readings.
- No more quizzes (after today).
- Project presentations on Wednesday.
Extra credit (Academic/Artistic)
- CS Extras Thursday: Summer opportunities in CS.
Extra credit (Peer)
- One acts Friday at 8pm and Saturday at 2pm and 8pm and Sunday at 2pm.
- Wednesday at 4pm, Dance Projects in the Wall.
- Piano Recitals, Dec. 8 at I’m not sure in SL.
Extra credit (Misc)
- Mental Health Campus Resource Fair. TODAY at 4pm in JRC 209.
- Newtown movie Tuesday night.
- Newtown was an act of extreme violence
- Whoops! Your exams are due on Tuesday night.
- If you see the movie, you can have an extra day on Exam 4.
Other good things
- Swim meet this weekend. (Friday 6-9 or so; Saturday 9-5 or so.)
- YGB concert Saturday at 2p.m.
- Composition class concert tonight at 7:00 p.m.
- Jazz Ensemble Concert Friday at 7:30 p.m.
- Chamber Ensembles Saturday at 4:00 p.m.
- Collegium Concert Sunday at 2:00 p.m.
Notes on exam 4
I have responded to most of the prologues that I received by 8 am this morning. Here are some common notes.
Problem 1
- You can’t just add counters or use the debugger, since many of the “expensive” procedures are built in.
- Hence, you’ll need to think about which procedures are “slow” (in that they lo ok at the whole list).
- You may want to write down on paper the procedures each calls and think about wheth er each is “fast” or “slow”.
Problem 2
- I’d recommend direct recursion (without an accompanying “tally”).
- I’d recommend that you use
pair?rather thanlist?to check whether something is a sublist. (We did say that the input was well formed.)
Problem 3
- No changing the vector.
- No using vector append.
- No using lists.
- Good: Count the number of elements that meet the predicate. Then build the vector. Then copy.
Problem 4
- Remember that you need to use binary search.
- “use binary search” means “use the approach” not “call the procedure”
- Do not change the vector.
Problem 5
- The hard part of the problem is part e.
- You need to write about this problem even if you decide not to do it.
- We use
list-appendto make it easier to track costs.
Other
- The most common answer to Q3: “I’m going to do problem 6 because I enjoy whatz itdos and dislike trees.”
- The second most common answer: “I don’t really like whatzitdos, but I like tre es even less.”
Questions (on the exam or other)
- Do you realize that the indentation is wrong on problem 1?
- I do now.
- Do you owe AK an apology?
- Yes.
- “PLEASE! In the interest of safety, the use of rollerblades or scooters is forbidden in academic buildings.”
- But, from now on, the use of any wheeled vehicle on the 3rd floor of Noyce is discouraged, except if it is necessary.
Quiz
- If you finish early, review the self-checks from the reading.
- Bonus one point question: When we make CW scoop out all of the water in
the Noyce elbow using a teaspoon, approximately how many gallons will
they need to remove?
- Simplified version: Approximately how many gallons of water are now in the Noyce Elbow (or were there at 1pm.)?
Lab
- There should be six parts (a-f) in exercise 1. Please reload if you don’t see all six parts.
- Then reload about five more times fo rall of the other things I forgot
to fix. Sorry!
- I have tenure, it’s okay if I admit mistakes on a public web site.
- Writeup 4f, 4g, and 4h.