Testlib what is testlib? Testlib is simple library which helps you to write * checkers * validators * generators * interactors for programming competitions problems. You can find latest release of the library on : https://github.com/MikeMirzayanov/testlib/ Problem development management system Polygon completely supports testlib. https://polygon.codeforces.com/ How to use? Easest way is to read c++ sources in the checkers/, validators/, generators/ and interactors/ folders. Also some classes and methods in testlib have documentation.