I send my CV to a friend at Google on May and after receiving a No Thanks from a recruiter after 3 weeks, instantly received a phone screening invite from another, it was weird but I wouldn't ask, In the interview there were a few normal questions about my background and I was schedule for a coaching session. At some point in the week they change me to a Youtube recruiter because of my background and after that I was invited to a on-site interview (that was schedule about a month after), where I was through a 5 interviews in which apparently I answered the problems too fast because it was 1 problem per interview but because we had some "extra time" in 4 of them I got 2 programming problems, the fifth one was one problem about system design and a normal programming problem. After I came back it took about 2 weeks to receive the notice that my reviews were weird because there were good and neutral good reviews but one was a no hire, so they decided to gave me another set of interviews (2 phones interviews) that apparently went well but my recruiter need to chase one of the interviewers for 3 weeks to get the feedback. And well they noticed me that the hiring committee had approved me and then the team matching would start, at this time was mid December so nobody were in the office or weren't easy to reach out so we postponed it to starting January and after some calls we found a mutual match team and I got my offer and said yes. So about difficulty of the problems they are easy if you practice, I was studying in preparation about two months before the interview.