> It's -stupidly- rare for people to 'figure out' the question in an interview; even those who appear to are just dredging it up from having seen it somewhere.
Isn't the point of those questions more to evaluate your problem solving skills (coming from someone who has never been up against those questions), and not to determine if you can actually solve the problem, but how you're able to justify your answer?
Allegedly, yes. But the person who has seen it before is able to arrive at an answer, have it be ideal, and justify it, a lot more readily than someone who has never seen it before. That's what the OP was even saying; if he's seen it before he does fine, if he hasn't he struggles and freezes up. That describes a LOT of people. It's also why I tend to interview with trivial questions, things that algorithmically have no trick at all to them (or we give them the algorithm).
Isn't the point of those questions more to evaluate your problem solving skills (coming from someone who has never been up against those questions), and not to determine if you can actually solve the problem, but how you're able to justify your answer?