[Jeema3000]

Knowing all about data structures and other computer science implementation-related stuff means exactly nothing if a person can't think creatively enough about how to approach a real-world problem to begin with. Those data structure CS questions are down in the weeds and you haven't even figured out if the person can get down to the weeds if you're asking those sort of questions in a first-round interview.

I mean think about it: do you approach programming tasks top-down or bottom-up, usually?

Critical thinking is the most important skill IMO, and it can only be tested by giving someone open-ended questions on how they would approach real-world assignments, preferably in a low-pressure take-home test kind of thing - again IMO...