I'm constantly surprised when I read articles like this one, or when I take interviews myself, that noone considers how the employee deals with a "project as a whole". Toy logic problems or algorithm optimisation tell you nothing about how good that person is at actually working as a software engineer. Do they care about code unit tests and code coverage? If they find a process missing - no continuous integration or something - do they just mumble and make do or do they find out why and, if necessary, implement it? Are they capable of delivering quality software, or can they merely write neat, optimised algorithms?
Those are questions a manager should be asking, ie, outside the scope of the interview I'm conducting. They're also the easiest to fake. Everybody knows the answer is to say they write test cases for every change before they check it in. That's way easier to memorize than any coding puzzle solution.
I've had some frustrating experiences where the obviously talented candidate was nearly passed over because they didn't use the right software engineering buzzwords while at the same time the manager came close to overruling the technical veto because they felt some other idiot sounded like a good fit.
Teaching someone to write unit tests is, imo, far more likely to succeed than teaching someone to understand recursion.
