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Unformatted text preview: CS 135 Winter 2011 Brad Lushman Assignment: 4 Due: Wednesday, February 9, 2011, 9:30am Language level: Beginning Student Allowed recursion: Structural Files to submit: list.rkt , lde.rkt , poly.rkt Warmup exercises: HtDP 8.7.2, 9.1.1 (but use box-and-pointer diagrams), 9.1.2, 9.5.3, 10.1.4, 10.1.5, 11.2.1, 11.2.2, 11.4.3, 11.5.1, 11.5.2, 11.5.3 Practise exercises: HtDP 8.7.3, 9.5.4, 9.5.6, 9.5.7, 10.1.6, 10.1.8, 10.2.4, 10.2.6, 10.2.9, 11.4.5, 11.4.7 Here are the assignment questions you need to submit. 1. Perform the Assignment 4 questions using the online evaluation “Stepping Problems” tool linked to the course web page and available at https://www.student.cs.uwaterloo.ca/ ˜ cs135/stepping The instructions are the same as A03; check there for more information, if necessary. Re- minder: You should not use DrRacket’s Stepper to help you with this question, for a few reasons. First, as mentioned in class, DrRacket’s evaluation rules are slightly different from the ones presented in class; you are to use the ones presentedin class. Second, in an exam sit- uation, of course, you will not have the Stepper to help you. Third, you can re-enter steps as many times as necessary to get them correct, so you might as well maximize the educational benefit. 2. In the file list.rkt : (a) Use the template for functions that consume a ( listof int ) to write count-positives , which consumes a ( listof int ) and produces a count of all the positive numbers in the list. (b) Use the template to write the predicate some-negative? , which consumes a ( listof int ) and produces true if and only if at least one number in the list is negative. (c) Use the template to write the predicate alternating? , which consumes a ( listof int ) and produces true if and only if the list alternates between even and odd numbers. For example ( cons- 1 ( cons 4 ( cons 5 empty ))) and ( cons 2 ( cons- 3 ( cons- 2 empty ))) are alternating. The empty list is considered to be alternating. A ( listof int ) of length 1, consisting of a single integer, is also considered to be alternating....
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This note was uploaded on 10/02/2011 for the course CS 135 taught by Professor Vasiga during the Winter '07 term at Waterloo.
- Winter '07