Amazon Web Services Software Development Engineer II interview questions

First, I had an Online Assessment to complete. There were 2 Leetcode style questions and some scenario based technical as well as work style assessment questions. After 4 days received an Email from the recruiter that I had passed the OA and my availability for the Final loop interview. There were 4 rounds in the loop. 1 based on Leetcode hard question. I on Object Oriented Programming. 1 on System design and 1 on again coding where you write a function to transfer logs from a warehouse. I didn't understand the warehouse question.