Amazon Senior Developer interview questions

I had got call from amazon recruitment team for telephonic interview. I was waiting for the telephonic interview on scheduled time. In between I had sent a mail to HR asking for detailed JD. There was no response from them at all. Just before 5 minutes of scheduled time, got call from interviewer saying he is busy and can not take interview. It only shows how they manage their time / plan and respect others time. I had wasted lot of time for this interview. First round of telephonic finally happened on re scheduled time. Question were very basic like matrix multiplication, difference between override and overload, some distributed computing. I could answer them well and even interview acknowledged that it is correct. I was very hopeful of getting into next interview. To my surprise, I got a mail saying that i have not cleared first round. I don't know how they evaluate when interviewer himself acknowledged that answers are correct. Whole thing is badly handled.

I got three phone interviews. It's first time one company gave me three phone interviews. These three interviews finished in two weeks. and one week later, I got rejected. each interviewer will ask one algorithm question. For me: 1. how to reverse a string? 2. how to merge two sorted linklist? 3. find LCA for two nodes of a binary tree. pretty easy, ahh? I thought i will get the offer, but I am just not lucky.