On Tuesday, 31 July 2018 at 00:52:22 UTC, 9il wrote:
> Are competitors allowed to use mir-algorithm and mir-random? The libraries can be used for graphs (Tarjan algorithm), matrices/tensors, nd-iteration, RNGs, interpolation, and distributions?

Sadly, no: most of the time, language compilers on the server side are provided as they are out-of-the-box.  I'll try to explain why.

When a language is added to a competition, one of the goals for the organizers is to keep the whole thing fair.  Different languages have different pros and cons already as they are, and what is an implementation-heavy problem for one language is solved in a couple lines with another.  So, the availability of several programming languages already puts some burden on the problemsetters: at least for important competitions, they have to come up with problems which don't play too much into the strengths of any particular language, and that means knowing what to generally expect of all the languages.  For example, most problems don't rely on number crunching with integers above 64 bits, since C++ is notoriously lacking in this regard.

This all gets a new dimension if a platform decides to supply additional libraries.  Once it's done for one language, there are no clear boundaries: if we get mir-algorithm for D, we will have to at least install Boost for C++, and numpy for Python, and the users of other languages also ask for their favourite libraries, which are in turn more powerful than Boost, and so on.  And it would take significant expertise to balance such requests so that no language has too much of an unfair advantage or disadvantage.  It takes a bit of expertise too to keep the libraries in all languages working and up-to-date.  All the way, the problemsetters now have to avoid a different set of topics, changing with new libraries being added.

Yet another factor is that there are central competitions perceived as the most important, which are currently ACM ICPC World Finals for university teams, and their regional contests.  Many platforms strive to act as training grounds for the important competitions.  So when the World Finals, which are understandably conservative, don't do X, it's a disincentive to do X for the training grounds too.

So, the default approach is to keep each language at a bare minimum.

> It would be nice to have this feature, as mir-algorithm can be a good default library for competitive programming. Plus competitors can add additional graph algorithms.

It may still be reasonable to ask for additional libraries on the platforms where the focus is not some big competition: e.g., perhaps no for ACM ICPC archives, perhaps yes for interview training sites.  For a particular platform and a particular cause (e.g., a training course for a learning platform), it's entirely possible to have D with mir-algorithm installed on the platform.

Ivan Kazmenko.