If given a question about reversing a string, it lets you ask the interviewer questions like:
* Do you want to do it in-place or as a copy?
* Is it an ASCII or Unicode string? If using Unicode, I assume you want to reverse on grapheme cluster boundaries?
Asking these questions let you as a candidate demonstrate your knowledge.
If the candidate doesn't ask these questions, the interviewer can ask follow up questions like.
* What is the time/space complexity of the algorithm? (Easy answer!)
* How does this work with UTF strings?
I don't particularly like the question, but have been in interviews where this exact question was used. From the discussion with the candidate it did very quickly weed out inexperienced developers. I was amazed at how many people applied for roles and had no knowledge of these concepts.
> Do you actually reverse strings here?
We've also tried doing more in-depth code exercises, which are more applicable to our business domain. That didn't work much better, and required upfront work from the candidate, which isn't always fair on them.
Anyways - happily not involved in the recruiting process any more.