Amazon Intern interview questions

I has two calls over two days. The first call, the guy was polite and helpful. He asked me a couple of questions about projects that I did for school. Then asked a couple of Big O questions and finally how to reverse a string. I reversed a string using a library and he pointed me to using arrays. The second guy started drilling me with questions ranging from Big 0, to describing different sorts, to the difference between inheritance and polymorphism. He asked me to write an inorder display function for a binary search tree. Finally at the end he asked me about what I would do if my web site was running slow. For five minutes I guessed at what it could be, he did not like my answers and at the end of the interview told me that I should test each component on its own. If I gave him the right answer I would of have the job, but I did not.