[Index of Lectures]

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Lecture 09—Fixed arity trees

Before Lecture

Before lecture 9, please be sure to work through the List Abbreviations video in the Binary Search Trees module.

During Lecture

The starters for this lecture are:

• m06-bst-dd-starter.rkt
• m06-bst-render-starter.rkt
• m06-bst-lookup-starter.rkt
• m06-bst-count-starter.rkt
• m06-bst-count-odds-starter.rkt

After Lecture

First complete the lookup, count, and count-odds starters that did not complete during lecture.

This material is harder than before — and at the same time, once you use the recipes and especially what the recipes tell you about working with arbitrary sized data, it isn't that hard. What's hard is letting the recipes guide you.

As usual, working through all these examples is a great way to really learn this material.

Then you can make two improvements to render-bst:

• Introduce a helper called render-key-val that does the whole number->string, string-append :, and all that.
• Add functionality to draw lines and make things look a little better. (Don't make this harder than it needs to be. First start with pencil and paper. And trust the natural recursions.)

Also watch the remaining videos from Module 6a and complete online questions. If you feel you need more practice work all the BST design problems in the videos on your own. Remember, you don't learn by watching, you learn by doing. Finally be sure to complete the Before Lecture section of the next lecture before the next class.

The solutions for this lecture are:

• m06-bst-dd-solution.rkt
• m06-bst-render-solution.rkt
• m06-bst-lookup-solution.rkt
• m06-bst-count-solution.rkt
• m06-bst-count-odds-solution.rkt

Be sure to complete the before lecture section of Lecture 10 before that lecture.