After working on a problem, when I hit "run & check", I was unexpectedly brought on a page with an error message saying something like: "Only authorized users can solve problems". Apparently I had been logged out without realizing it. So I logged back in, but my code was gone. No way to recover it.
So, here's my humble suggestion: when someone hits the "run & check" button without being logged in, it's ok that they get an error message, but they shouldn't be brought to another page, In that way they could at least copy their code, before logging back in.
author:[username] - Returns posts by user
associated with the given user.
tag:[tag_name1],[tag_name2], ... - Returns
posts associated with the given tag(s).
phrase - Returns posts that contain the word
or set of words in title or text.