My biggest problem with solving simple programming problems tends to be the memorization involved with different languages, especially if I haven’t used a particular language in a while. More often than not I’ll go through my resume and remove (or limit mention of) languages that I used for only a short time or simply haven’t used in a while.
For example, I feel quite competant with dealing with basic database issues, but without having touched a database in a few years I’d have to look up even the most basic sql statements, so I wouldn’t claim to be a capable database programmer, though after a couple of weeks I could be at least a moderately good one.
Recursion is a similar problem with different languages. Some languages don’t allow it at all, and others have very specific restrictions that make it a little harder to just jump in and say we’ll just make this call here and make sure the conditions are in line to stop the whole mess from self-destructing.
In other words, I have a terrible memory, but I can still answer most of those questions with whatever language I’ve been using recently. I simply have to maintain my resume to avoid being asked questions that would send me to the books (or the web) to find an answer that should just spring to mind immediately.