Microsoft Program Manager New Grad interview questions

First, an on campus interview with a business operations / analytics manager, in person interview with lots of engineering managers. Second, onsite interview with engineering and program managers. The team i was interviewing for seemed super engineering oriented (their product is kinda like a microsoft engineering consultancy) so I had more engineering/cs questions that the average interview

I talked to the HR representative at our school job fair and was scheduled for a on-campus interview. The HR is very professional and friendly in terms of replying emails, answering questions...etc. However, the interview itself went pretty bad. I knew they will ask you the position you're looking for and ask you questions based on that (e.g., ask you design questions if you're looking for a PM position and algorithms/ coding if you're looking for a SDE). After I told the interviewer I'm looking for a PM position he kept asking me about algorithms and even asked me to optimize it when I gave him the answer. Since the questions weren't hard, I was able to answer them quickly, but he just kept going deeper and deeper until one point I couldn't come up with answers. I talked to other people who interviewed with other interviewers and they said theirs weren't that bad so I guess I just got unlucky.