Amazon Software Development Engineer interview questions

I had a total of 4 interviews. My 1st interview consisted of problems based on trees and linked lists. I was asked to code all my algorithms. My 2nd interview consisted of questions based on algorithms, he was interested in my logic and did not ask me to code anything. My 3rd interview asked me a basic algorithm questions and we went back and forth discussing the solution. After he was fully satisfies he asked me to code it. There were some mistakes in the code which he hinted at and I quickly corrected them. My 4th interview was mainly to check my motivation for the job and the interviewer asked me to design an elevator system.