Amazon Software Developer interview questions

Two standard phone screens with different developers. First interview asked simple concepts and practices associated with object oriented programming. There was also a heavy focus on data structures. Since Amazon is a global company, they are interested in scalability and efficiency when it comes to development. First Interview Questions: 1) What is encapsulation and polymorphism? 2) Describe linkedlists, arrays, stacks, queues, priority queues, heaps, and binary trees. What are their complexities and benefits? 3) On a server in a directory with 50,000+ HTML files how would you find and return a count of phone numbers? 4) What is the difference between binary and hex decimal? 5) Design/Code a method that multiples two numbers without using the multiply operator. And what are some tests you would implement (i.e. black box, white box)? Second Interview Questions: 1) Given a list of acceptable words (dictionary), how would you check to see if a given input is on that list? Complexity and efficiency? i. How would you complete this task with a dictionary that is too large to fit in ram? Complexity and efficiency? ii. Now given two input words how would you find and return all available words in between the two words? (i.e. input1= "Cat", input2= "Fish", return all words in between) Complexity and efficiency? 2) Given a singlyLinkedList, write a method that reverses the order of the list. Complexity and efficiency?

interview was lasted 40 mins. strted with basic programming things. And tht led our conversation onto more technical as i have to design 2 codes. 1st was kinda intresting and 2nd was challenging but i did well :)