You are weeding out all candidates who understand Unicode. This is exactly the sort of problem that a good engineer would keep an eye out for because it's almost certainly going to explode with edge conditions if you try to do it the "obvious" way.
Unless you're giving that problem and then hitting the input with a string that includes directional formatting characters. Because that's exactly what is going to happen in real life.
The only good thing about that question is at least you didn't ask them to casefold the string.
No, not all, probably not even many. There are lots of candidates who know Unicode who would just say “I’ll assume that we have just ASCII characters unless you think I should consider Unicode” and if you say the latter, then they can say “Well, I could reverse it by just ensuring the text appears right to left, or perhaps by reordering each grapheme cluster to the end, or something like that. Let me know if you want one of those, otherwise I’ll just write it assuming you mean A”.
The magic of engineering isn’t doing what you’re told. It’s understanding and solving a problem someone has told you about.
My org doesn’t need the guys who need exhaustive instructions to take the next step. It needs those who can make good Bayesian inferences, reason inductively, and figure out problems.
So yes, it does filter out people with lots of knowledge who nonetheless lack these skills.
Hey, listen, the way I see it is that you don't want to work with a company like us and we don't want to work with you. It's an eminently compatible situation.
Unless you're giving that problem and then hitting the input with a string that includes directional formatting characters. Because that's exactly what is going to happen in real life.
The only good thing about that question is at least you didn't ask them to casefold the string.