TL;DR: I couldn't register on usaco.org (Gmail verification bug), so I built OJCloud — all 484 USACO problems (2011–2024, Bronze → Platinum) on a modern judge with partial scoring, 16 languages, real-time per-test-case verdicts, progress tracking, and both ICPC/IOI contest modes. Everything uses standard I/O. Register with just a handle + password — no email, no OAuth, no waiting. Hello, Codeforces!
I've been using USACO problems to train for years, but practicing them on usaco.org always felt unnecessarily painful — so I built a judge that just works.
The friction is real: Gmail users often don't receive verification emails and the only fix is emailing the contest director personally. Pre-2020 problems silently require file I/O — your code compiles, runs, produces correct output locally, but gets WA on the judge with zero explanation (this is the #1 cause of "it works on my machine" reports). There's no dashboard to track what you've solved, and the submit button is buried at the bottom of a static archive page.
I put all 484 USACO problems (2011–2024, Bronze through Platinum) on OJCloud with a proper judge. Everything uses standard I/O — no file I/O surprises.
What you get
- Partial scoring — no more guessing whether you failed 1 test case or all 20. You see exactly how many tests pass out of the total.
- 16 languages — C++20/17/14/11, Python 3, PyPy 3, Java 21/8, Kotlin, Go, Rust, and more
- Real-time judging — live verdict per test case as the judge runs, not a spinner followed by a wall of results
- Progress tracking — solved count, acceptance rate, activity heatmap, submission history. You know where you stand.
- Polygon-compatible checkers — 10 built-in testlib.h checkers (wcmp, lcmp, fcmp, ncmp, rcmp, hcmp, yesno, ...) + custom checker support
- Contest system — both ICPC and IOI scoring formats, live standings
- Bilingual — full English + Vietnamese interface, auto-detected from your location
Try it
484 problems and 5,000+ test cases are live. Register with just a handle and password at app.ojcloud.net — no email required. Pick a USACO problem, submit, and see the judge in action.
Feedback welcome — comment below or join us on Discord where we discuss USACO solutions daily.
Thanks to MikeMirzayanov for Codeforces and testlib.h — many of our design decisions were inspired by Polygon.
