Round 2 Amazon

Hai.Is this sushma!!! This is Brian, Software Development Engineer from Amazon. I woke up from my bed and started looking for the note i had written for the very famous question to explain about oneself. I always have problem answering that. To my mystery he had a different googly. So Sushma, Why Amazon? I was not at all prepared for that question. I had real tough time answering the same. But i had no choice to skip it. Mention any project you had worked on which made you proud? That was the same question i was asked for in the first round too. It was simple for me to answer. He then started asking questions based on whatever i spoke and the discussion started here. He later asked if i am comfortable with C++. Common!! i am a java programmer. He then started asking technical questions.What is the difference between a class and an object..difference between boxing and unboxing..those were pretty straightforward to handle. I went on explaining things my way. Then started more on oops concepts. Explain polymorphism without quoting an example. That sounded like a GRE question to me. I literally had to give an English definition for polymorphism without using technical jargon's and scenarios to support my explanation. Then came the question on collections to name all concrete classes and interfaces. Then started with the famous topic "data structures". Given a binary tree how would you reverse it. I gave him two solutions both o(n) with took more space and o(n) with constant space complexity. Then another googly. Design a simple file system. That made me dizzy for a moment. But i had to buckle up and start solving it. I came up with a simple file system design with two main concrete classes a File and a Directory and started rolling out my design. Then came more questions on how better the design could be improved. His questions were dicey sometimes. But i had to handle it the best possible way i could. Then came the famous Fibonacci sequence generator. I used a simple iterative approach to solve the same. He asked if there could be any alternative solutions. Of course the old enemy recursion is there always. I then had to justify my choice with strong reasons. Sushma, do you have any questions for me? I was greatly relaxed to know that the interviewer is finishing up the interview. I checked the time. It was exact 1 hour since we started the call . At last things did end on a good note. I was pretty satisfied with whatever i could come up with at that particular time. I hope to hear from them soon.