Grading Criteria for Assignment 4
You should consider this homework to consist of "two problems" -- the first is just the function that calculates the Doomsday rule, and the second is the bit that prints a calendar. Each of these should be graded on the usual 2-point scale, so it should be out of 4 points total.
As to what to try out -- you should look at all the examples that caused you trouble when you were writing this. :) Make sure you try some leap years and non leap years, try 1900 and 2000. Look for months that are 31 days and start on a Friday or Saturday (like May 2004), one that is 31 days and starts on a Sunday (May 2005, say), and a February that starts on a Sunday (like Feb 2009).