Microsoft Sr Software Engineer interview questions

At first, I received an online algorithm task via hacker rank, one medium, one hard. Afterwards i had a quick chat with a recruiter. After passing these, i was scheduled 4 back top back interviews lasting for 45 minutes with 15 minutes pause. On all of these, you start by talking about your previous experience and afterwards there are practical/techical questions. The first one had OOP design, second was behavioral interview, third algorithm on HackerRank, the fourth was a system design. The technical questions were not that hard at all, i failed because i expected them to be much harder and my brain found complexity when there was none

Interview was nice, I liked the team and office. The HR department was generally responsive and nothing raised any red flags. I didn't get position afterwards anyways, but I the whole iring process seems to be fine as it is. Later I found they plan to relocate the office, but it is still going to be in moderate walking distance.