CSC 207.02 2019S, Class 37: Traversing graphs

Overview

• Preliminaries
  • Notes and news
  • Upcoming work
  • Extra credit
  • Friday PSA
  • Questions
• Lab

Preliminaries

News / Etc.

• We are back to lab days. Yay!
• Electronic evaluations are live in some classes, but other folks (including me) don’t want you to do them outside of class, so those are marked “unavailable”.
• Buffalo buffalo Buffalo bufallo bufallo buffalo Buffalo buffalo.

Upcoming work

• Reading for Monday
  • Wikipedia: Prim’s Algorithm
  • Wikipedia: Kruskal’s Algorithm
• No lab writeup today.
• Exam 2 due last night.
  • Free extensions until Sunday. Let me know if you need longer.
  • Those in by tonight will be graded by Monday.
• Final exam: 9am or 2pm, Thursday or Friday of finals week.
  • I’ll try to have a sample final ready early next week.
  • Let me know which of the four times you plan to take the final.
• No more homework!
• No more quizzes!

Extra credit

Extra credit (Academic/Artistic)

Extra credit (Peer)

• Sunday, May 5, 2pm, Herrick (?), Grinnell Singers and the Grinnell Orchestra
• Tonight, 9pm Gardner, Opening Band for Gardner show: “Sorry We’re Late”. Opening for “Girl K” with “Blizzard Babies”
• Tomorrow The Grinnellian, Saturday.

Extra credit (Wellness)

• Tonight CS Picnic, Friday Night.
• Pella Tulip Festival.

Extra credit (Wellness, Regular)

• 30 Minutes of Mindfulness at SHAW every Monday 4:15-4:45
• Any organized exercise. (See previous eboards for a list.)
• 60 minutes of some solitary self-care activities that are unrelated to academics or work. Your email reflection must explain how the activity contributed to your wellness.
• 60 minutes of some shared self-care activity with friends. Your email reflection must explain how the activity contributed to your wellness.

Extra credit (Misc)

Other good things

Friday PSA

• All things moderation
• Pay attention to the law
• Know what is right for you; be comfortable with your choices
• Consent is absolutely necessary

Questions

So, how do we traverse a graph?

Um. Maybe with recursion.

For breadth-first traversal, we can use a queue.

For depth-first traversal, we can use a stack. (We can also use recursion.)

Lab

What’s the default value in a boolean array?

I don’t know, let’s try.

$ jshell
|  Welcome to JShell -- Version 11.0.1
|  For an introduction type: /help intro

jshell> boolean[] vals = new boolean[33];
vals ==> boolean[33] { false, false, false, false, false,  ... lse, false, false, false }

I love REPLs. (Read-Eval-Print Loops; the traditional interaction with Scheme, also available for Java in JShell)