QCoder
Solve quantum circuit puzzles in timed competitive programming contests
QCoder runs competitive programming contests about quantum computing. Instead of classical algorithms, each problem asks you to write a program that builds a quantum circuit to prepare a given state or carry out an operation. Your solution is judged automatically and ranked on a contest leaderboard.
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About QCoder
It trains quantum gates, state preparation and the quantum algorithms behind them. It suits people who already know basic linear algebra and the quantum circuit model. Earlier problems in the archive are a good way in.
It runs in the browser and you sign in to submit. Contests last two to three hours and happen a few times a year. Past contests stay open for practice. Problem statements are available in English and Japanese.
On Breakpoint since 25 Oct 2026.
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