I don't trust anyone who comes back with quick answers without any hesitation or pause. I remember a lecture from a while ago, I can't remember who was giving it but they were someone well known, where they asked people to implement bubble sort. The results that came back ranged from something like 20 lines to 2000 lines and every single one had bugs. I don't know how anyone who works in this industry for any length of time doesn't follow up every answer with, "...but there's probably some problem that I'm not thinking of at the moment".