> The discussion with those who don't know the solution is useful, of course. Agreed, the discussion on these questions is the whole point, not whether you can

> The discussion with those who don't know the solution is useful, of course. Agreed, the discussion on these questions is the whole point, not whether you can come up with a "correct" solution (and I tell candidates this up front). I generally draw a small example input with a cycle, and ask what their list-reversing solution will do with it, which I feel makes it much less of a trick question. "Can you work out what the code you just wrote will do with inputs that don't meet the assumptions you made?" seems like a fair thing to ask anyone who will be required to write code that handles untrusted data.