Amazon Software Developer interview questions

I had two phone interviews with different individuals each lasting about and hour. The interviews were technical in nature. However, they were less about language semantics and more about algorithm design and data structures. The questions inevitably led to the topic of performance in both interviews. Big -O evaluations were asked about the code that you implemented over the phone.

Hi, There are 2 rounds of phone interview and a on-site to get into Amazon. I cleared first phone interview in which they asked me only two questions. One was to convert int to string without using any library and second one was to generate random numbers again without using any library. After 2 weeks I have to write a follow-up mail and then they set up aother phone interview in which they mostly asked about data structure, sorting and C/C++ question. I waited for 4 weeks and after 2 follow-up mail, I received a reject mail.