Though to be honest, Google uses those kinds of questions and apparently treats them as useful, so I'm not sure why you'd have wanted to work there.
Eventually got fed up with their process, told the interviewer what I thought of it and hung up.
(which, to point out at least one upside, is the only way I've ever discovered of getting a company I don't want to work for to stop bugging me with recruiter spam)
Naturally if there is no option for the discussion when somebody does not know the answer off the top of their head then this would be really absurd and pointless situation.
This question is not good for selecting out somebody for their specific knowledge, but it is in my option a good one to prune out candidates that manage to demonstrate their general ignorance about the field.
Ah ok, I guess I misunderstood you. Though this "absurd and pointless situation" does in fact happen: There definitely is a class of interviewer who will expect off-the-top-of-your-head detailed knowledge (like being able to remember bubble sort's details from just its name).
This is absolutely absurd. I have a CS degree from Berkeley (universally considered one of the best CS programs in the world), and I spent the last few years on an unusually CS-focused team within Google (specifically, artificial intelligence). Off the top of my head, I could easily imagine not remembering what exactly bubble sort is. What's the use of retaining the details of an algorithm that's literally held up as the "don't do this" solution to sorting? The most I can imagine being useful is knowing the theoretical best case average complexity of a sort. And my job is wayyy more CS-focused than the average engineering job at Google (let alone elsewhere). You heavily overestimate how useful rote memorization is to real-world productivity.
Whether a candidate _understands_ these concepts, on the other hand, can actually be illuminating. If you described bubble sort to someone and asked him to describe the complexity, then you're getting all the signals you're describing about CS understanding and education. (though there's controversy about the usefulness of these skills as well)