The files in this repo are my solutions to various problems in Project Euler

https://projecteuler.net/

I think PE247.java is particularly clever, although it is not the cleanest solution.

Project Euler is a series of challenging mathematical/computer
programming problems that will require more than just mathematical
insights to solve. Although mathematics will help you arrive at elegant
and efficient methods, the use of a computer and programming skills will be required to solve most problems.