Amazon Software Development Engineer interview questions

Contacted via in-house recruiter. They were having a recruitment day in my area, so I went straight to the 1:1 interviews. There were four interviews (three with managers and one with another SDE). The schedule for the way went: interview 1, interview 2, short talk with HR, short break, interview 3, interview 4. The questions ranged from OO design to data structures. As usual, I had to give the {run,space}time complexity of each solution. After answering most questions, I had to describe how I would scale it up to Amazon.com-size. I received a phone call 2 business days later. They informed me that they weren't moving forward with me. I appreciated the phone call... rather than receiving a generic email.