Codevita 2020

Anyone knows of any platform where I can submit solutions to previous year’s Codevita questions and get my code validated against private test cases like in cp websites? I know there’s one called edyst but is there a free one? There’s not much sense in spending 3k when only a few days are left. Any suggestions will be appreciated. Thanks.

Another Question: To those who participated in earlier Codevita/Mockvita rounds, is using auto, stoi, to_string, etc C++11 features supported in Codevita compiler?

Some of them are previous year’s question.