LeetGPU

This is the challenge set for LeetGPU.com. We welcome contributions and bug reports!

Overview

Each challenge includes problem descriptions, reference implementation, test cases, and starter templates for multiple GPU programming frameworks.

Challenge Structure

Each challenge contains:

• challenge.html: Detailed problem description, examples, and constraints
• challenge.py: Reference implementation, test cases, and challenge metadata
• starter/: Template files for each supported framework

Contributing

See CONTRIBUTING.md for guidelines on contributing new challenges or improvements.

PR review bot

.github/workflows/review-bot.yml runs on every non-draft PR (opened, synchronize, reopened, ready_for_review). The checks job runs the same checks as CI (black/isort/flake8, clang-format, mojo format when .mojo files change, python scripts/validate_challenges.py). Then the bot decides:

1. Deterministic rules (.github/review-bot.yml, easy to tune). Needs a human if the PR touches .github/**, scripts/**, challenge_base.py, runner/grader/checker code, dependency files, .clang-format, .flake8, .pre-commit-config.yaml or CLAUDE.md; edits an existing challenge's challenge.py (its reference_impl is the grader); adds more than one new challenge; adds unexpected files under challenges/; renames or deletes files; changes more than 400 counted lines; or any check fails. In a new challenge folder only challenge.py counts toward the limit (html and the 6 starters are boilerplate).
2. LLM review of the diff (only if the rules pass), with the list of existing challenges so it can catch duplicates. For new challenges it checks the quality bar from CLAUDE.md. Diff over 80k chars ⇒ not safe. The diff is treated as untrusted data; the model must return strict JSON {safe, risk, reasons}.

Safe + low risk ⇒ APPROVE review. Anything else ⇒ COMMENT review with reasons, review requested from ishaan-arya and shxjames, needs-human-review label (created if missing). Missing key, failed call, or invalid JSON ⇒ human review (fail closed).

The review script and config run from the base branch and PR code is never executed in the job that has secrets. Fork PRs are skipped by the review job (no secrets / write token on forks), so they need a normal human review.

Setup

• Setting: Settings → Actions → General → Workflow permissions → Allow GitHub Actions to create and approve pull requests.
• Secret REVIEW_LLM_API_KEY; variables REVIEW_LLM_PROVIDER (openai for any OpenAI-compatible API, or anthropic), REVIEW_LLM_MODEL, optional REVIEW_LLM_BASE_URL.
• Optional GitHub App identity: secrets REVIEW_APP_ID and REVIEW_APP_PRIVATE_KEY.
• Unit tests: node --test .github/review-bot/.

FAQ

Does my solution's time include compilation?

No. The score is only the kernel run time:

• CUDA / Mojo are compiled on the server before your run starts.
• CuTe DSL is compiled with cute.compile before the timer starts.
• Triton / PyTorch / JAX JIT-compile on the first calls, which happen during the functional tests and 2 warmup runs. Those are not scored.

The reported time is the median of 15 timed runs on the performance test. Each run gets freshly generated inputs and an L2 cache flush first. The timer covers your solve call plus a device sync. It includes Python launch overhead for Python-based languages, but not compilation.

Compilation does count toward the overall wall-clock limit of a submission (about 40 s for everything: compile, all tests, warmup and timed runs). A very slow compile can cause a timeout even when the kernel itself is fast.

Why did a tiny code change make my kernel noticeably faster or slower?

Run-to-run variance on shared GPUs is a few percent. Changes to indexing can also change what the compiler emits, for example vectorized vs. scalar loads or extra integer ops in the address math. Compare a few submissions before reading much into a single result.

License

This problem set is licensed under the CC BY-NC-ND 4.0 license.

Copyright 2025 AlphaGPU, LLC. Commercial use, redistribution, or derivative use is prohibited.