Was that (implement sort) the main point of the question? Especially given the 15 minute time window this sounds more like some kind of fizzbuzz-style question (here's a basic idea, can you translate it to code somehow in some language?). Usually when interviewers give me that kind of thing they're literally fine with bubble-sort (which I'd hope anyone could code on the fly), or even just assuming some appropriately shaped sort function exists and writing the rest of the code around it.

No that's not what the question is asking. You should be using the standard library sort function (or making one up if you can't remember the specific API).