It's actually just how you would find a number in a paper phone book.

No it's not. Some parts of a phone book search resemble a binary search, but choosing your pivot and processing the last few pages do not. I've never seen someone not do a linear scan at some point.

But all that's irrelevant to my point. Asking for a bog-standard solution to an industry-standard question is in no way a demonstration of someone's originality. You don't ask it to prove that they aren't doing "mimicry" you ask it to prove that they can, and thus are capable of learning the basic tools of their trade from others.

I'm pretty sure I independently invented binary search when I was a child (as have many others).

It's a pretty darn obvious thing to do when you're physically handling an ordered collection of records.

It's the recursion (or parameters to functions in recursion that kills most candidates). It's pretty intuitive in the head.

But I agree, plain vanilla binary search is easy.

People are free to implement an iterative version.

Exactly

> Probably only 1 in a million people could figure out how to do it if they didn't already know how it is done elsewhere.

They already know how it is done elsewhere; it's how one finds a word in a (paper) dictionary or an book index.