Meta Software Developer interview questions

The interview process for me was uberly long. I wasn't planning on applying to Facebook, but a recruiter reached out to me mid-december on LinkedIn. I thought "what the heck, it's a great company" and got back to her the next day, but she was leaving for the XMas break. No more communication until early Jan. Connecting on the phone was a pain, as first she didn't call until 15 minutes after she said she would. I had stopped standing by the phone and went to email her when she did call, so missed it. We emailed and set something up for an hour later. This time she called 30 minutes late. No apologies or anything. Sigh. She advised that I put all of my other interviews before the Facebook one so that I could get practice, and then signed me up for a free interview review course they run. I went and things were all great, so I told them I was ready. Queue another 2 week pause while they tried to answer a question I had asked before scheduling me. When I finally made it onsite for an interview (mid-late feb), I had expected it to be a full day of interviewing, but instead it was a 30 minute screen before I could do the *actual* interview. In all fairness, I should have seen that coming. But anyways, did the screen and got a response before I had even left the parking that they wanted to schedule my full interview. I also got a call from my recruiter that afternoon to give me interview feedback. I thought that was awesome, as most people don't do that. I can't say how useful it was as I had no negative feedback from my interviewers and her advice was just "wow, keep doing whatever you just did!" but it sounds like it could be useful if things don't go perfectly the first time around. Anywho, by this time I had multiple other offers with deadlines on them. I went ahead and scheduled the final round interview for the following week, but ended up canceling the day before as I had decided to go with another company. This seemed to irk my recruiter, despite the fact that she was the one who told me to interview with other companies first and I had been upfront about that and the associated timelines during the whole process. When initial contact and end offer are 2.5 months apart, you can't expect someone to be sitting idle that whole time... The only reason I still rank this as a positive experience is because I had a secondary recruiter I worked with coordinating onsite logistics (the girl who first contacted me was out of state) and he was awesome. If any of you get the chance, work with Charlie. He's direct and super straight forward and knows that candidates are people with multiple options and treats you as such. I do a lot of mentoring and will certainly be sending any of my mentees who expresses interest in Fbook Charlie's way; he's a real gem.