CSC151 2009F, Class 38: Trees
Admin:
* Reading for tomorrow: Analyzing Procedures.
* One of my former advisees made the front page of NYT Arts & Leisure
* Congratulations! to men's soccer.
* You know that you're in too small a town when the local radio
station reports on when one of your students had surgery.
* (Or maybe that's just football in Iowa.)
* Exam 2 returned. I hope to have an answer key ready later this week.
* THERE IS MORE TO LIFE THAN GRADING!
(So comments on the second half of the exam are a bit briefer than
those on the first half of the exam.)
* Are there questions on Lab Writeup 5?
* Are there questions on Assignment 7?
Overview:
* Notes on exam, lab, and assignment.
* Thinking about trees in terms of cons.
* Thinking about trees recursively.
* Writing recursive tree procedures.
Questions on Writeup 5
* The pictures should be turned in in hardcopy. Please don't scan them.
Notes on reverse:
* Drawing on physical whiteboard. (Sorry.)
* What is a list?
* null is a list (the empty list)
* if L is a list, (cons X L)
* Looks a lot like our def'n of the natural numbers
* 0 is a natural number
* If N is a natural number, 1+N is a natural number
* cons can take non-lists as the second parameter
* A color tree is a pair structure defined as follows
* A color is a color tree
* If C1 and C2 are color trees, than so is (cons C1 C2)