I can't speak to any particulars in this situation. I thought I would add that it's not necessary to know C++ (I don't :o). It is true that there are people who work on projects that are entirely written in C++. However, there's not generally a requirement that applicants write solutions in a particular language and pseudo code is usually fine.

I'm interested how this came about. They usually either try to match people who know common languages or they do more generic problems which don't depend on language. One important thing is if you said you knew C well (or even only "working knowledge of") then it's perfectly reasonable for them to ask you to write it in C instead of Java/Python/etc. Did the interviewers state they didn't Java beforehand? Did they say they knew another language you'd mentioned you knew on your resume?

My interview experience actually involved them hammering me on the languages I said I knew but wasn't an expert in. This is likely as they were trying to find out whether I was lying (or, put kindly, overstating) on my resume. From what I've seen there are a few people who put every language down that they've ever written hello world in ;)

(disclaimer: recent intern from Google Sydney office)

They won't give you feedback for the same reason they don't disclose their search algorithms: information about their process can be used to game the process.

I see the same behavior with VC's -- no usable feedback. It's like in poker -- there's no game-theoretic advantage to show your cards if everyone else folds.

It's also arrogant not to even let someone know what the specific position involves. It's a solid reason not to interview with Google if you're not going in there on the basis of contacts.

The reason for that is that at the time of the interview there are usually many different positions you could wind up being slotted into.

In many cases this is still true at the time of the hire.

In a few cases this is still true at the time the person starts on the job.