Amazon Non Software Development Engineer interview questions

I applied online and was gives two time slots to choose from for scheduling the interview. It was two telephonic calls of 1 hour each. Both were done using a shared doc. The interviewers were very patient and helpful. Was a pleasant experience though I wasn't given an offer for the position.

It was on-campus interview. I applied before the school career fair and got scheduled the interview during it. There were two questions asked by two different interviews. The first question was: given the inorder traversal of a n-ary tree where every node can have either n or 0 children, and is marked "p" if that node has n children, or marked "q" if that node has 0 children, try reconstruct that tree. The second is a design question: given two huge user action logs where each log item has a user id, a document id and access time, try find out the documents that are accessed by two or more users and on two or more different days.