Ahoy mateys!

Invite

TL;DR: Come solve 2 problems a day in September 2025 Long Challenge from September 1 through September 7, UTC 5am time.

Each day will feature an easy and a hard(er) problem. The harder problems are Div2 D+ level, so I imagine the contest will have something interesting for most participants. Hope to see you there!

I want to thank speedermen and wery0 for their help testing the problems and the platform. These guys have been a joy to build stuff with; if you see them somewhere, please give them a big upvote <3

Meta

A couple weeks back, I posted about vibe coding a programming challenges platform. I was rather happy with the output, so I fine-tuned it further and added some more features:

• Contest message log. No pubsub notifications, just a simple table below the problem list that displays notifications directly from the database. It has automated notifications for e.g. a problem being solved for the first time, and allows me to insert arbitrary messages for e.g. problem statement changes.
• Profile page. You can now pick how you want to be displayed — your GitHub username (if you OAuthed with GitHub), your Google name (if you OAuthed with Google), or Player #1234.
• Groups. I needed some way for users to organize into custom leaderboards, and really tried to avoid copying the corresponding Advent of Code feature — but in the end, it turned out that with my leaderboard architecture it was the only viable option.

In the backend, I fixed a critical database interaction bug (I used an old-school connection pooler instead of pgBouncer, which resulted in a stress-test of any magnitude making the database unavailable for 1 minute), and added metrics through PostHog, which honestly is an amazing tool even on the free tier.