CIS 313: Lab 0 Intermediate Data Structures

CIS 313: Lab 0 Intermediate Data Structures 
Overview
This lab is an introduction into lab procedure and a review of Python. The purpose of this
assignment is:
• An overview of using the unittest module in Python to test your code.
• Learn how to write test cases in Python.
• Learn how to use exceptions in Python.
• Learn how to submit your work using Gradescope.
You should implement the two functions (lcm and gcd) yourself. You may not use an
external math library to compute them.
Description
Begin with the template code in lab0.py, which outlines a class named mathOps. mathOps
stores two integers, u and v, and provides two functions to compute operations on those
integers:
• gcd computes the greatest common divisor of u and v.
• lcm computes the least common multiple of u and v.
You need to write enough test cases to ensure that your code performs properly in a
comprehensive set of situations. For example, listed below are some possible inputs to be
used in the test cases. A few test cases are given to you in the file test lab0.py. Please make
sure you test your program runs properly for all the possible edge cases, including
malicious inputs like strings or floating point numbers (instead of integers), extremely large
numbers like 2
100
, etc. You should make sure the program ends gracefully in these situations,
throwing proper exceptions and not crashing.
Please implement Euclid’s algorithm for computing the GCD. Your implementation should
run in O(log(u + v)) time. (This should automatically be the case, unless you do something
unusually inefficient.) LCM can be done using GCD as a subroutine, so it will also run in
O(log(u + v)) time.
Testing
u v gcd lcm
29 31 1 899
Example inputs and outputs: 0 45 45 Exception
45 0 45 Exception
5 Inf Exception Exception
The exceptions for the last example should indicate that one of the inputs is infinite. The
exceptions for the two middle examples should indicate that the LCM is undefined in those
cases.
You should not change the name of any of the classes, files, or existing methods. Arguments and return types for public methods should also be left unchanged.
CIS 313: Lab 0 Intermediate Data Structures Fall 2022
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Files to Submit
You should submit the lab0.py with the filled in methods. You should also submit the test
lab0.py file with all the test cases that you had written to test your code. These two files
should be compressed and uploaded in .zip format under the filename “submission.zip”.
Please make sure you select the lab0.py and test lab0.py files and compress them. Do not
compress the folder named submission directly which will result in another subfolder named
submission being created after converting to zip format. The screenshot is an example link
on how to do achieve this. Once you submit your files to Gradescope, you will get the results
and the score for your assignment. If any of the test cases fail, you need to modify your code
and resubmit until all the test cases pass in order to get full credit.
Grading
Typically, half of your grade will be determined by attempting to implement the correct data
structure, and half will be on correctness and style (style will be discussed in labs). This
assignment only has the correctness component. There will be 20 points possible for this
assignment. Since this is the first assignment, I will try to provide as much assistance as
possible during the labs and office hours to make sure you get full credit and all your doubts
are clarified regarding submission and writing test cases.
Very important things to keep in mind:
Facts about LCM and GCD and things that I have assumed:
• GCD of 0 and 0 is 0
CIS 313: Lab 0 Intermediate Data Structures Fall 2022
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• GCD of 0 and any other number (say 45) is the number (45).
• The absolute value for negative numbers (| − 6| = 6) should be used for calculating
LCM or GCD.
• LCM of 0 and any other number is undefined (should raise an exception)
• LCM and GCD of infinity and any other number is undefined (should raise an exception)
• If floating point numbers are used, the ceiling value is used. (e.g.: 39.7 is rounded to
40)
Your code will be tested against the following invalid values:
• Strings
• Infinity
• Very large numbers
• Zero and negative numbers
So it is of paramount importance that you are aware of raising exceptions and using the try
and the except block in Python. You should be able to raise some inbuilt exceptions like
OverflowError, TypeError, ValueError, etc. in Python. The descriptions of the types of
Exceptions can be found in Exceptions list.pdf. You need not write your own exceptions
for this assignment. This might seem challenging initially but we are there to provide as
much help as possible. And we will do our best to ensure that you score full 20 points in
this sample assignment. Please get as much assistance during the office hours as possible.
Good luck!!
Note: Passing the test cases carries some points. And some points will be allocated
for style. If you use proper variable names and your code is comfortable to read, you will
probably get full points for style. Only in rare circumstances will you lose points for style.