Amazon Software Development Engineer interview questions

Five hours interview. Four interviewer all come from the same group. Each of them charge one round. There will have two questions each round, the first one is simple and the next one will be improve/refine the problem before. I believe if you are a bachelor always work with normal algorithms and data structures you will feel quite comfortable with this kind of interview. Graduate student is not necessary in this position. They only focus on your basic capability. I am graduate student and the intervire shcedule is not a good time for me. I perpare two days for this interview after my 3 final projects, I meet a issue when I hit the third round and ask for a hint, so i think I am not the perfect candidate in that group. I found that when they ask me to talk about my projrcts I feel that they are not that kind of "research guys". So again I think they are placing the emphasis on the basic capability...