I have missed out on jobs purely because my mind blanked on simple puzzles like this. I've also done brilliantly on such puzzles in other interviews -- I know how to implement a linked list in a non-pressure environment. I've never had a complaint about my abilities from someone I've worked with.

So yeah, I think it's a questionable practice at best, but I do understand it. I have also considered the possibility that it's not the fault of the question but the questioner, for making it a high-pressure situation.

Personally, I prefer to ask open-ended questions about a problem the candidate has already solved -- recently, if possible, and covering both coding and process problems. If they can bring code-samples, fantastic.

I have missed out on jobs purely because my mind blanked on simple puzzles like this. I've also done brilliantly on such puzzles in other interviews -- I know how to implement a linked list in a non-pressure environment. I've never had a complaint about my abilities from someone I've worked with, so maybe I shouldn't think that I've missed out on jobs, I should think that they've missed out on me.

So yeah, I think it's a questionable practice at best, but I do understand it. I have also considered the possibility that it's not the fault of the question but the questioner, for making it a high-pressure situation.

Personally, I prefer to ask open-ended questions about a problem the candidate has already solved -- recently, if possible, and covering both coding and process problems. If they can bring code-samples, fantastic.