LinkedIn Developer interview questions

I find the one of my friend who hired by linkedin reffered me at Oct, then after 1 week I receive the confirm email from HR. Then the first phone interview at Nov 1st, the problem is Nested List Weight Sum. I solve this question by DFS iteration and recursive. Then the second phone interview was 11 16th, the problem is roman to integer and integer to roman combined.

Contacted by recruiter through a resume database. Completed a Hackerrank coding challenge, 30 min phone screen with recruiter, and then 2 one hour technical phone interviews. The interview questions were pretty standard (algorithms/data structures). Would've rated the experience as positive except my recruiter was pretty unresponsive throughout the process (for example, they would ask me for my availabilities and then not reply to me for a week, then schedule my interview for a time that I told them I wasn't available at).