> Defensive coding. Check for nulls, empty collections, etc. While this is important to avoid bugs in your algorithm, I've had candidates who spent way too long on this and it comes across as inexperienced. I don't really care that you know how to check null-ness, if you just mention "assume the parameter is not null", it's more than sufficient to me.
Thank you for the feedback, I have tweaked the wording accordingly (:
Unless one is already intimately familiar with interviewing, it's hard to distinguish the do and don't.