Amazon Software Development Engineer interview questions

I was contacted by a recruiter for FBA team and asked me to fly in for onsite interview. On the day of the interview, I was taken to a room and said whole of my interview process will be dealt in the same room. First interview was with the director of the team. Basic questions on string, but I was very much surprised by the authoritative manner expressed by him. He was not ready to hear what I tried to explain nor tried to understand. So in the mid of interview process I almost lost interest. I was not given time to rewrite the code, as we mostly don't get optimized solution at first go. I did (int)c - 97 to get the ascii value of a character from a to z and mapping it to 0-25, which took him by surprise and asked why i dint use toascii. Second interview was with some manager. It was an easy question. though i coded it, i din come up with a solution which is common as it dint strike me. It was my fault. and there was a design question, but not enough time. Third interview was with senior developer. It was a system design question. It went pretty well. I was able to answer and come up with solutions. Fourth interview was with a developer. This guy also showed his attitude. Though the question was pretty simple, I made an error which i immediately rectified. Also I must say got a nervous. It was 3 hours long interview with no break in middle except for water or coffee.