[enriquto]

> If you really think anyone (..) can be reasonably expected to derive an optimal solution to problems like these...

I can see an usefulness to questions like these. Maybe you are precisely not looking for reasonable but for exceptional people. Or maybe you want to see how the candidate behaves in front of a difficult and concrete problem, even if you do not expect them to solve it.

[tropicalia]

Even if you do not expect them to solve it.

The unstated implication in most cases is that you damn sure are supposed to solve it - or get "flushed".

As to "seeing how the candidate behaves in front of a difficult and concrete problem" - I'm sure this is what a lot people who ask questions like these think they're achieving by asking them. But again, you have to ask yourself if that's what the questions actually do permit you to assess.

My sense is that it's not - and that questions of this sort are mostly, well - cheap gimmicks, basically.

[lordnacho]

I don't buy that at all.

Think about the potential hidden states (already knows the answer vs blank) vs the evidence you could get from the person answering right or wrong. What should your prior be? Surely that there's a very large chance this person is not a genius. Now how much is that going to move, given that by far most people are not geniuses?

To put it another way, what would you do to impress someone following your reasoning? I would pretend like I didn't know it, and then act out the miraculous direct line to the answer.

As for looking at how people behave in front of a hard problem, what on earth do you know about that? Do you have evidence connecting people's behaviour to subsequent on-the-job performance, both for people you hired and those you didn't?