Seems to be great fun, but I can submit a solution - the submit button is not active. What should I do?

Moreover, are there any other ways of signing in? I have a lot of my private projects on Github and I wouldn't like to share it with any other site.

And the last tip: you may use the #include <bits/c++.h> in the snippets to make it shorter. It simply includes everything from std.

Hi. The submit button is disabled because you are not logged in. There're should be a hint. I believe every developer has a GitHub account, that's why I've chosen it as the OAuth provider. Your private repos will stay private, the site receives only your public information available for everyone in the Internet. Great advice about <bits/c++.h>, thanks.