CMPSCI 187: Programming With Data Structures

David Mix Barrington

Fall, 2011

Homework Assignment 3

Posted Wednesday 2 November 2011

Due on paper in lecture, Wednesday 9 November 2011

Corrections in green added 5 November 2011.

Correction in brown added 6 November 2011.

• Question 1 (10): Do Exercises 6.1 and 6.2 on page 181 of L&C. In 6.2, make the three code fragments run sequentially. If any remove operation throws an ElementNotFoundException, assume that this exception is caught immediately and the the catch code does nothing. (So, in effect, the remove becomes like the poll method in the Java library Queue interface.)

• Question 2 (10) Do Exercise 6.3 on page 18 of L&C. "Each of the implementations" means the L&C versions of ArrayList and LinkedList, not the java.util ones.

• Question 3 (15) Do Exercises 6.4 and 6.5 on page 181 of L&C. In Question 6.4, there are in fact no variables in L&C's ArrayList class called head and tail. They mean front and rear -- there is no front in the code, but as they say on page 153, the "front" location in this implementation is always 0. So you should say when rear can be 0.

• Question 4 (15) Do Exercises 6.6 and 6.7 on page 182 of L&C.

• Question 5 (10) Do Programming Project 6.1 on page 182 of L&C. You should write (on paper) a class that extends L&C's LinkedList class and implements their StackADT interface.

• Question 6 (10) Do Exercise 7.1 on page 204 of L&C, looking up the ordinary definition of a valid Java identifier.

• Question 7 (10) Do Exercise 7.2 on page 204 of L&C, but also cover the case of y = 0 (remembering that x⁰ is always 1, even if x = 0).

• Question 8 (20) Do Exercise 7.5 on page 205 of L&C, but modified as follows. We define sum(i, j) to be equal to i if i = j, and otherwise to sum(i, k) + sum (k+1, j), where k is the number (i+j)/2 (where "/" is Java integer division, rounding down). (This used to erroreously say "(1+j)/2".) You may assume that neither i nor j is negative. Trace the calculation of sum(1, 7).