Amazon Software Development Engineer interview questions

Applied online via third party site, received an email later that day to setup a phone interview. The first attempt at an interview (Saturday) didn't happen because my interviewer had to leave early. One thing to note was that, I asked the HR person who was going to interview me and it changed on the day, so don't be surprised if that happens. I was able to reschedule the week after. My interviewer was again with a different person then I expected and we had trouble with the phone lines so we couldn't hear each other that well. Because of that he skimmed past questions about my experience and went straight to coding. I understand given the circumstances it was probably the best option but because of that I wasn't able to build a rapport with my interviewer and that put me off my game a little. I am however not making excuses, you've got to work with what you've got. I was asked 2 tech questions, not particularly difficult but also not particularly obvious, well for me that is. I believe after a bit of figuring out and some help from him I was just about to finish the first question but the Collabeit site kept erroring so we had to stop the interview. Having not completed either question, he then throw me a bone and said, email the answers within 2 hours. I was able to answer #1 but #2 had me stumped, the actually question he asked was relatively simple, the parameters in which I could answer it however, was not in a way I was accustomed to. Needless to say I couldn't answer the second question and didn't have enough time to document my thought process in my different attempts to find solution. I pretty much knew I wasn't going to be considered for a face to face interview, so after a week went by with no communications I emailed the HR lady asking if I was still in consideration, which I knew i wasn't, she told me that were still reviewing my interview feedback. The day after I was officially declined.

On campus interview. Four round and each takes 45 mins. Questions include data structures(can be done easily with hash table and arraly/link list),Object Orient Design(how to model Card and Deck) , tree algorithms (find if two trees are identical; if a tree is a BST) and debugging. No difficult question but no idea what I do not get the offer.