Exactly. Questions that have a super optimized answer that's probably non-intuitive and unlikely to be arrived at if you've only spent a few minutes exposed to the problem. These are basically puzzle questions in disguise.
In general I think there are two kinds of coding questions that are worth asking. Straightforward implementation based questions that should be solved basically as fast as the candidate can write, assuming they're familiar with the basic techniques. These are in the same vein as fizzbuzz and generally just give you a sense of the techniques the candidate has mastered (basic programming, bit-wise operations, recursion, etc.) The other kind are open ended questions that help show problem solving skills, knowledge of different algorithms and data structures, etc. These sorts of questions don't have the same variance as the secret puzzle questions. The amount of time to throw up a fizzbuzz implementation if you've seen the problem before should be about the same as if you haven't. And the same goes for open ended questions that are more about design, thinking, etc.
And of course you always want to factor in the problem of dealing with candidates who are nervous, in an unfamiliar and uncomfortable situation, and not operating at peak performance. You shouldn't expect production quality code for complex problems in those situations, you should be looking for code that gives you data.
In general I think there are two kinds of coding questions that are worth asking. Straightforward implementation based questions that should be solved basically as fast as the candidate can write, assuming they're familiar with the basic techniques. These are in the same vein as fizzbuzz and generally just give you a sense of the techniques the candidate has mastered (basic programming, bit-wise operations, recursion, etc.) The other kind are open ended questions that help show problem solving skills, knowledge of different algorithms and data structures, etc. These sorts of questions don't have the same variance as the secret puzzle questions. The amount of time to throw up a fizzbuzz implementation if you've seen the problem before should be about the same as if you haven't. And the same goes for open ended questions that are more about design, thinking, etc.
And of course you always want to factor in the problem of dealing with candidates who are nervous, in an unfamiliar and uncomfortable situation, and not operating at peak performance. You shouldn't expect production quality code for complex problems in those situations, you should be looking for code that gives you data.