PHSCO Fall 2025 - Internal Files

If you want to solve these problems for yourself, visit the official public gym on Codeforces or visit our website for more information on PHSCO.

If you are interested in hosting your own round on Codeforces, darkkcyan has written an excellent tutorial on how to create problems in Polygon. For practice, you might want to try importing one of my problems onto the platform!

This repository hosts most of the internal files used during the creation of the Fall 2025 PHS Computing Olympiad, including:

• Raw .tex statements (and style files)
• Solution Files
• Generators
• Validators
• Checkers

Hopefully, these provide a greater insight into the problem-setting process and inspire you to create your own programming competitions!

Terms of Use

Please do not use or modify these problems for use in your own competitions! I strongly discourage this for several reasons:

• Plagiarism is bad
• It grants an unfair advantage to people who have taken part in PHSCO
• Using problems with publicly available solutions is the easiest way to invite cheaters
• From my own experience, problems that are simply modified copies of other problems usually don't turn out to be good problems unless the fundamental idea has been changed! (If in the process of modifying a problem, you find that you've created a new problem that requires a complete solution overhaul - that's inspiration! Just make sure to write the problem yourself, and maybe give some credits in an editorial.)

If you believe your use case is valid (i.e. an educational practice round with no prizes), feel free to email me at [email protected].

If you reference these problems in a blog post or elsewhere, please provide credit and/or a link to this repository!