Amazon Intern - Software Engineer interview questions

The interview was simple with three questions: 1) remove duplicates in an array 2) hash table implementation in C 3) find max in an array Since it was so easy, and I had given all the answers with correct complexities. Still did not get the offer.

Applied online, got an email saying that they would like to set up an interview. I then had two 45 minute phone interviews. After that, they emailed me saying that I have made it to the third interview, which was another 45 minute interview, of same format. Two of the three interviews used collabedit, which is an online text editor (for programming) that lets the interviewer and interviewee to view/edit the same code. So they would ask a question, I would write the code, and they would see it and be able to assess me from it. The third interview was all verbal, but I was asked to write a short piece of code, that I emailed to them shortly after.