I understand what you're saying, but I still fail to see how all of this translates into not being a team player. That really has nothing to do with this at all. If the interviewer still wants a solution based on the facts as they lay on the table, he can always ask again. The first is answer is still the best answer in my opinion, because it is much closer to a real-world situation and it shows a deeper contextual understanding of situation. It also implies experience.

Anyone can repeat someone on StackOverflow who says that function X really is faster than function Y. That's hardly an accomplishment. It's like asking someone to perform a basic non-trivial calculation out of his head -- why bother?

That's the problem -- you're smuggling in non-obvious, hidden assumptions about the framing of the interview[1] and then penalizing someone who doesn't share them, without giving them the chance to isolate what those assumptions were and why they should use those in this context.

So they're getting rejected for a reason other than technical skill.

[1] "Okay, we're going to talk like I've already fixed problems A, B, and C, but not X, Y, and Z, because we obviously don't have time for a full interaction that is open-ended enough to allow for all of those to be an issue, and you're being judged on how quickly you focus on and solve the X/Y/Z."

I think you misconstrued the intent of my original post. I was merely trying to point out that the interview question was (in my experience) based on a very questionable premise.

I wasn't saying anything about how one ought to handle such a situation during an interview.

I totally agree that a response akin to "Your question makes wrong assumptions. Let's move on to the next question." would be completely inappropriate for an interview, or if the same issue arose in a normal work situation.