Yes, my understanding is that the parent comment is complaining that since it took people with phds years to derive an algorithm for the first time, that we sho

Yes, my understanding is that the parent comment is complaining that since it took people with phds years to derive an algorithm for the first time, that we should never expect anyone to implement one in an interview. But, as with a concept like 0, making the cognitive leap to understanding that there should be a way to represent the lack of something is counterintuitive (indeed, consider Tony Hoare's billion dollar mistake. The "right" way to represent the absence of an object is a hard problem). However, once you've been exposed to it, it's not particularly challenging to rederive the necessary pieces. So yes, complaining about BFS is, imo, akin to complaining about being asked what the result of the arithmetic operation `35 - 12 - 23` is.