Amazon Software Development Engineer interview questions

My friends hand in my resume and I get the on-site interview directly. The interview process is basical, first have a lunch with several amazon employee. Then each candidate was brought to the room and start the interview. I had four interviews in total, and I did perfectly in the first one, the second one and the last one. I think they fail me because I didnt do well in the third one. So, just bear in mind that Amazon is very picky, if you screw up one of the four interviews, then you fail.

The recruiters were friendly; aced through 2 telephonic interviews and was invited to the on-site interviews. On the day of interview, I was interviewed by 5 amazonians; 4 tech and 1 lunch interview. I believe I did well in all but the first interview... After a week, I was notified that I wasn't selected to make a job offer. I guess I was disappointed, as I thought I did well, but wasn't made an offer. But, then your performance is relative to the other candidates they interviewed...