About one month ago I asked Xu Han (admin of the Virtual judge) if it's possible to add my own problems (that aren't present in any online judge) to some contest in Virtual judge, and we worked together to find a way to do this, and here is it, you can now add your own problems to Virtual judge. Let's see how to do.
- Register on Codeforces polygon, create a problem and add statements, tests, checkers, etc.
- Create a mashup here.
- Add the problem to your mashup. Follow the instruction in this comment.
- From contest panel, go to "manage inventions" → "invite users" → add vjudge1, vjudge2, vjudge3, vjudge4, vjudge5.
- The problem is added to Virtual judge now!
- To add your problem to your contest, choose "gym" from judge list and add your problem using its code (contest code + problem code, i.g. 207753A).
To see an example, here is my added problem to Virtual judge: Arpa as an ARPA :P (Hard, Fixed).
P.S. Deleting problem is not available now, but Xu Han said that he will make it available soon.