Amazon Software Development Engineer Intern interview questions

First interview went horrible. Interviewer was very unresponsive during entire phone call. Answered 2/3 questions. Third question regarding graph algorithm I was not able to solve and I believe that is what caused me to not get offer. Know your data structures and algorithms very well.

I sent them my application online and received an email to set up two phone interviews. They were supposed to be consecutive but the first interviewer bailed which was annoying and unprofessional but they scheduled me again. The first interview was with a chinese guy; so i had some trouble understanding his accent. He basically did a quick run through of my resume and then asked me the difference between an abstract class and interface. He then asked me to give him pseudocode on a java function to find the word count on a string. The third question was to find the first unrepeated character in a string. The second interview was more technical. He went through my resume and asked me quick questions about my coursework and why Amazon. He then asked me the differences between a BST, Linkedlist and Hashmap. He then told me to write a simple hash function based on a input string key. The last question was to find the intersection of two arrays. In all these cases, the efficiencies were asked.