Unprofessional recruiter, very friendly during the intro call, then after the phone screening if you don't pass they just won't tell you anything at all. The interviewers also specified that for any kind of questions you could email them or the recruiter.. Why would you do that?

Phone screen via Hacker Rank. I first had two questions, the second of which had a fairly amiguous specification, that I understood differently that what the interviewer intended. So they organized a second phone screen with a single question that had two follow up steps with increasing difficulty. I solved it all; correctly (the interviewer tried it himself on a number of inputs and it worked) with a well structured solution. As it turned out I was rejected because of "verbosity of my solution". I strongly suspected the interviewer was a Python developer freaked out by seeing a Java constructor, because that's about as much verbosity there was to the solution. He also suggested an "improvement" that would have made it marginally shorter at the expense of modularity, so a rather questionable tradeoff, I'd say. I've been interviewing for 10+ years, sitting on both sides of the fence numerous times and have no problem admitting flanking an interview, but getting a bogus feedback is fairly frustrating.