Lab: Searching

Summary: In this laboratory, we explore different issues related to searching.

Contents:

• Exercises
  • Exercise 0: Preparation
  • Exercise 1: Testing Our Procedures
  • Exercise 2: Extending sequential-search-vector
  • Exercise 3: Observing Binary Search

Exercises

Exercise 0: Preparation

a. Start DrScheme.

b. If you have not done so already, please scan the reading on searching. In particular, you should look at the sample procedures. Make sure that you understand the purpose of get-key in binary-search.

c. Add the procedures from that reading to your library of utilities.

d. Create a vector, names, of a dozen or so lists, each of which contains a last name and a first name. Order the list by last name.

Exercise 1: Testing Our Procedures

a. Using sequential-search-list, search for the letter #\a in various lists of characters.

Note that it's probably easiest to create a list of characters with string->list.

b. Using sequential-search-vector, search for the letter #\a in various vectors of characters.

c. Develop some tests for search-list-for-keyed-value. For example, you might create a list of cartoon characters and their sidekicks and search the list for character or sidekick.

Exercise 2: Extending sequential-search-vector

Write a procedure that takes a predicate and vector as parameters and, using sequential-search-vector as a helper, finds a value in the vector that matches the predicate or returns #f if no such value exists. (Like sequential-search-vector, this procedure searches vectors; unlike sequential-search-vector and like sequential-search-list, this procedure returns a matching value, rather than an index.

Exercise 3: Observing Binary Search

Add calls to display and newline to the definition of binary-search, so that it prints out the values of lower-bound and upper-bound each time the kernel procedure is called. How many recursive calls are made as binary search finds your name in the list names? How many are made in an unsuccessful search?