Meta Design Verification Engineer interview questions

There were 2 rounds. During initial phone screen, they share code pad and gave me 2 coding problems. Had an on-site interview of 4 rounds. Questions were hard to solve - but the interviewers give you hints

I had a technical phone interview for the DV position with Facebook. The interviwer was not talking clearly. Also he was not very interested.I felt like the whole process was a drag for him. I got an email from recruiter that I was not selected.