Amazon Software Development Engineer interview questions

I went to school's career fair where amazon held interviews. The whole interview took 90 minutes with 2 interviewers. The questions are pretty straightforward. The interviewers are quite nice and professional. I was given a lot of hints, but I misunderstood one of the hints and screwed up that question. Question: what is hashtable? what is BST? compare them

I got a call through on campus selection process. I had 4 interviews. Each interviewer were asking questions specifically on each area like databases, algorithms, object oriented concept, and puzzles. I think I did well in 2 interviews but OOPs concept questions were on case studies: like define classes for automating a elevator, fury system to go from one island to another. Rest of the interviews were really good. They were trying to understand how well you know about each technology.