Amazon Software Engineer interview questions

Amazon contacted me after receiving my resume through a conference database. They asked me to complete a 90 minute online coding assessment, where I was asked 3 different (relatively simple) coding problems (eg determine whether or not a LinkedList contains a loop). A little over a week later I heard back from HR saying that I had been selected to go to Seattle for an onsite interview. The interview started at 11:45, and we were first brought into a room where we had lunch and casually talked to employees about Amazon and living in Seattle (there were about 30 of us, all students looking for post-graduation entry-level positions). Then we each were assigned an interviewer and brought to a small room with a whiteboard where I had 45 minutes to first talk about a project I had worked on/experience I'd had in school or internships. Then I was given a coding problem that I had to solve on the whiteboard. After I was finished, I had some time to ask questions of my own. There were four interviews just like this in total, in which I stayed in my room and interviewers came in and out. Two of my interviewers were very nice and helpful if I got stuck, one of them was kind of uncomfortable because I was confused about the problem and was struggling a little bit, and the other one seemed to really dislike me, looking at me like I was an idiot every time I said something or wrote something (he also tried to trip me up by saying that it was necessary to manually resize an ArrayList in Java, which I knew wasn't the case but it got me a little flustered and he told me I need to do some more research after the interview). That particular interviewer was stressful, but the other three didn't seem to want me to fail. Overall I think that the people there were pretty nice, although maybe a little bit pretentious, but it is Amazon so I suppose they have a right to be, since many many people want to work there and they have the ability to select the best of the best candidates. It was also a little weird after the interview, since my last interviewer walked me to the lobby and left and there was no further discussion or convening. I also wish they had been courteous enough to give me a call telling me I did not get the job rather than sending me an email.