Amazon Software Development Engineer Intern interview questions

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

I went through two phone interviews. Amazon focuses highly on data structure related questions - linked-list, tree, BST, hash table etc. Among the 2 phone interviews, the 1st one was pretty easy - basic algorithm questions, concepts like your understanding of time complexity - simple problem to solve. I think they just test if you have basic knowledge of computer algorithms and you can write code. The second phone interview was a bit more advanced. It was on data structure and object oriented programming concepts - problems on data structure, OOP concepts. The phone interviews were 45 min long and asked to solve 2/3 problems.