[vinkelhake]

How does a rejection like that work in practice? Was that the question the interview hinged on?

A reasonable interviewer could just say "Alright, now can you do it without using the standard library?".

[markbnj]

I should be clearer. They didn't specifically reject me for that. There was just a sense that the interview wasn't going well from that point forward. They may just have felt that their request was clear and my response was smart-assed, and in truth that is probably fair.