>I have the impression most Google-interviewers (and similar dudes/dudettes) wouldn't. I wonder why

Perhaps that was rhetorical, but I'll answer anyway:

Being able to wire up existing libraries to accomplish a goal is a pretty low bar to set as far as proficiency goes. Google doesn't want code monkeys. The solution above is perfectly good from a software engineering perspective, but it doesn't show the depth of the candidates knowledge nor how strong their grasp of CS techniques is.

Google's interviews are more like IQ tests than software engineering tests, using CS as the measuring tool. When you're Google you can afford to be that selective.

I'm glad that you like my solution, but please note that, as another commenter said, it's a buggier version of the original regex I thought of ("^(dict|here)+$"), which I think should work but doesn't, at least not in Python.

I suspect it's because the match group is being replaced with the last match rather than added as another group, but it will work as a state machine, and is pretty much equivalent to the backtracking example in the article (although with much less code, and no memoization).

That said, I think that the reason interviewers ask about functions for which we have well-known implementations is to see whether or not you know how they work and/or could implement them yourself. Nobody will reasonably expect you to implement your own string comparison routine, but you could score points if, for example, you said Boyer-Moore for string searching rather than the naive iterative version.