CMPSCI 311: Theory of Algorithms

David Mix Barrington

Fall, 2003

Homework Assignment #1

Due Friday 12 Sept 2003 in class

(or earlier to hand-in box in CMPSCI main office)

All thirteen questions are from [L] and have the point values indicated.

• Question 1.1.5, page 8 (10):

• Question 1.1.8, page 9 (10): For (b), your job is to indicate, for any given two positive numbers a and b, whether you would choose to move first or second in the game where a and b are the starting numbers. (Hint: The number of moves in the game turns out not to depend on the player's choices but only on a and b. It might be easiest to determine this number and then answer based on whether it is odd or even.)

• Question 1.1.10, page 9 (10): You are not required to actually run your code on a computer, though of course this is a good way to check that it is correct. You are asked for two methods. The first takes ints m and n as input and returns an array [d, x, y] such that d is the GCD and mx + ny = d (or throws an exception if the input pair is not valid). The second takes ints a, b, and c as input and either returns an array [x, y] such that ax + by = c or throws a NoSolutionException. (This is Java terminology, equivalent formulations in another language are fine.)

• Question 1.2.2, page 17 (10): Indicate briefly how you went about finding your solution, along with presenting it.

• Question 1.3.1, page 23 (5):

• Question 1.3.6, page 25 (5): Note that you are not asked to provide the algorithm in question, just to answer questions about the specification of the problem.

• Question 1.4.4, page 38 (5):

• Question 1.4.9, page 38 (5):

• Question 2.1.2, page 51 (10):

• Question 2.1.5, page 51 (10):

• Question 2.1.6, page 51 (10):

• Question 2.1.8, page 52 (5):

• Question 2.1.9, page 52 (5):

Last modified 4 September 2003