Amazon Software Developer Engineer interview questions

I got the interview invitation one week after I applied online. First I had two phone interviews 45 minutes each. The questions are not difficult, for example, why you apply for amazon? Find the least common ancestor of a binary search tree. The definition of virtual function, polymorphism, etc. Then, I got onsite interview invitation. The entire interview process lasts for about 5-6 hours including a lunch interview. Onsite interview is much more difficult than phone screen. I got problems like coding boggle puzzle problem, reverse a binary tree and design a distributed messaging system, etc.

The interview was arranged through my university and occurred on campus. I met with one an engineer. He was pleasant, but not extremely friendly. The interview started by asking me a bit about my classes and previous work experience. We then talked about what exactly I was interested in doing at Amazon, things I liked about Amazon products, etc. I was asked what features I would want to approve on their website. There were three technical questions. The first question asked how you was something like, how would you find the most common word in a string. It wasn't really that difficult, and after talking it through with the interviewer, I wrote code for it. He seemed happy with my answer. Second, he asked me a question related to the first one but with about databases. I don't really have any database experience so I really struggled with this. Last, he asked what happens when a person goes on the Amazon website, as in what happens between the person typing "www.amazon.com" and the page loading up. I answered pretty well, but needed a little help. He was nice and gave me a few hints which led me to the right answer. Overall I felt positive about the interview except for the database question. The next day I received an email, however, saying that I hadn't been chosen for the next round. Oh well.