Another good one is the "does linked list have loop" question. If you don't know the answer, you have to figure it out from inspiration. Took over a decade for the first guy to do it.
Similarly for many other tricks.
I have never used it in real-life development, though.
> I have never used it in real-life development, though.
I'd wager both of these are true for the majority of technical interview problems, and I think that's exactly the point.
so, this question isn't testing if you can find a loop, it's testing whether you have enough experience to have heard of it. which is a fine enough thing to test for.
i understand your point, that questions are often designed poorly, but your example isn't necessarily a good one.