Amazon Software Development Engineer Intern interview questions

I had two on campus interviews at my school campus.Each interview started off asking about a situation with a project. One of them was if I had any bad team members and what I did about it. I forgot the other one. After asking about the projects and the details of it we went over technical questions. After two weeks after the interview I was given an offer.

2 back to back phone internviews , 45 minutes each ... .questions were mirror image of binary tree - both recursive and non recursive, which is better and why , etc, den roman equivalent of integer eg 10 -> X, 99-> XCIX ... den what is hashtable and hasmap , complexities