Supported Languages

omegaUp accepts submissions in a fixed set of languages — the language column on a run is an enum, so a submission is always one of the identifiers below and nothing else. The list below is that enum, exactly as the database defines it. When you submit through the API, you pass one of these short identifiers (e.g. cpp17-gcc), not a human-readable name.

Two conventions apply across every compiled language, and they trip people up if they don't know them:

• Your entry point must be called Main. There is no per-problem build configuration; the runner compiles by convention. The main source file (and, for languages that need it, the main class) must be named Main — Main.java with public class Main, a Main executable for C/C++, and so on. See Runner Internals for how compilation actually happens inside the sandbox.
• Where a language offers both GCC and Clang, the identifier names the toolchain explicitly (-gcc vs -clang), because the two occasionally disagree on borderline standard-conformance and a problem-setter may have tested against one of them.

The languages

C and C++

The workhorses of competitive programming, and the reason the C++ list is so long — each standard revision is a separate identifier so an older problem keeps compiling the way it always did:

For new C++ submissions you almost always want cpp17-gcc or cpp20-gcc.

Other general-purpose languages

The special ones

Three identifiers are not general-purpose languages, and knowing what they are explains a lot about who omegaUp is built for:

• kp and kj — Karel. omegaUp grew out of the Mexican Olympiad in Informatics, whose entry-level track uses Karel the Robot, a teaching language where you program a robot on a grid. kp is Karel with Pascal-flavoured syntax and kj is Karel with Java-flavoured syntax — the same language, two surface grammars, so a beginner can use whichever their class taught. Karel problems are a first-class citizen, not a novelty.
• cat — output-only. For problems where you don't submit a program at all, you submit the answer. The cat "language" means the runner simply treats your submission as the output to be validated against the expected output. It is how output-only and data-file problems work.