We would like to introduce FlandreOJ: https://flandreoj.com, an online judge built around a concise competitive programming roadmap. The judge currently has more than 700 problems, and we are actively adding more.

The website currently has 7 levels from 0 to 6. Each level is divided into fine-grained topics, and every topic comes with a curated list of problems.

For each topic, we carefully cherry-pick problems: classic ones, or problems with interesting observation and neat tricks. That is, we try to include problems you can learn the most from, hopefully giving you a shortcut to learning new algorithms and techniques.

The judge works best when used together with additional practice on Codeforces, AtCoder, and others.

Join our Discord server to discuss problems, send memes, report bugs, or suggest new problems: https://discord.com/invite/jRJAdqzjDT

GLHF!

P/S: Because the problem rating is quite random, we don't recommend filtering problems based on rating. Just use the roadmap directly.