Quantcast Software Engineer DevOps interview questions

I applied through the website. I was then contacted by a recuiter and we scheduled the first interview. The very first interview with the recruiter wasn't technical, it was about my past experiences and my general profile. I was then given a coding challenge. The challenge was about simulating the functioning of a spreadsheet calculator. I passed the coding challenge with great review scores (it seemed), so I was scheduled for a technical interview. The tech interview was done on skype. The interviewer first ask some simple computer science questions then he asked a question already posted here, the one for which the solution is the mean heap. I failed answering to this very last question so I failed the interview. During the tech interview the interviews has never talked about himself and about his role within Quantcast. I was only asked a set of questions and it seemed to me they are not expected you have some questions about the company. I didn't like this approach at all, furthermore, does failing to answer to a question make you a bad SW Engineer? I don't think so.