Codeforces has a feature of hacking, during contests. Here hacking doesn’t mean illegitimately breaking into a computer system.

In hacking, you can view the solution of others. If you think that you have a test case where the code may give the wrong answer. Just click on the hack and provide your test case.

After the end of the Educational Rounds / (Div. 3) rounds there will be an 12-hour period of open hacks — any visitor of Codeforces may try to hack any complete solution to a problem of the last round (either from a contest, or practice), the source code of hacking solution is available (you can copy the text and, for example, stress it).

This script helps in automating that process by scraping and extracting all the submissions of a particular problem and testing it on your local Linux machine.

This script can be used for random/custom testing, random testing uses generator.cpp which generates random inputs for the problem, contains many prewritten functions for generating PRNS, Random tree generator, shuffler. You can modify generator for a particular problem that you are testing.

Before executing the script update generator.cpp and correct.cpp which contains the attacking code (possibly yours) for that problem.

lily.cpp is a temporary file in the testing process which stores defender code temporarily.