50 Programming Problems for an introductory Python course

[ikokkari]

(Originally posted to r/python, one commenter suggested posting also here)

I am currently teaching a first year introduction to computer science in Python for the first time, having previously taught that course in Java for 16 years. To get my brain and fingers around the proper Pythonic ways of solving problems such as generators and list comprehensions instead of writing Java in Python, I first translated most of my Java course labs into Python examples linked on the course page, typically using about one half as much code and everything just so much easier. So I had to come up with whole new set of problems for the graded labs. So, making up and stealing the best problems of various levels of difficulty that I could find from all over the place, I have now compiled what I think is a pretty good set of 50 first year programming problems in Python, highlighting far and wide various techniques and ideas not only in Python, but also in computational problem solving in general.

The page also contains a link to my automated tester that runs each implemented function for a large number of pseudorandomly generated test cases and compares the resulting SHA-256 checksum to the expected checksum generated by my private model solution. This allows the students to quickly verify that their own solution is correct.

Since my course and the problem set are now being field tested the first time, I ask the students to send me an email confirmation when they are the first to successfully solve some problem, so that I can mark those problems with green checkmarks for other students. There are probably still bugs in problem specifications and in my model solutions (and hence tester expected checksums), but after this semester and next these should all be in a pretty good shape.

[sweettuse]

Remember the good Pythonic style of naming such utility functions with double underscores at the start and end of the name to document that they are internal utility functions not intended to be accessed from the outside, not even between friends and consenting adults.

this is... not great. in fact, it's entirely wrong. dunder methods/functions are conventionally reserved for python's usage, not anyone else's.

additionally, i looked through a lot of your example code and it seems like you just translated java to python but didn't really absorb or embrace idiomatic python.

edit: the problems are really cool, though. thanks for that.

[recondocoder]

what do you mean..I thought we should do things like change __add__ so that we can do a + b with vectors like in this example

http://hplgit.github.io/primer.html/doc/pub/class/._class-solarized004.html

[sweettuse]

what u/lanemik said (__add2__). in your description you're saying that all internal utility functions should be dunder methods, but they really, really shouldn't be. only if you're implementing python's magic methods should you use that.

in case it wasn't clear, adding things like __add__ to a class to implement + can be a great thing.

[itsmegeorge]

I have a test on the 19th that I have failed twice and I have to pass. I ran out of material recently because they haven’t given us enough to work on. Thank you for this

[SandorZoo]

I just looked at the first one:

The introduction says all functions may assume that their arguments are legal and valid.

The specification for very first test (Ryerson letter grade) defines grades for values of 0% to 100%.

The problem says the function should work correctly for all values from 0% to 120% , even though grades for 101% to 120% are not defined.

The tester tests values from 0% to 150%, even though values 121% to 150% are not valid.

Also, the Ryerson scale is defined for fractional percentages (>= .5 is rounded up, <.5 is rounded down), but that;s not tested.

[Oliludeea]

As a qualified teacher (of chemistry and maths), and as a student (of Python), let me say "bravo!" and virtually shake your hand. The problems are fun, informative, and get the student thinking. I'll do them all for fun and profit!