Amazon Software Development Engineer interview questions

There was one written and 3 tech rounds...and i couldnt clear the last round....Written had 2 questions on trees and most of others also was on trees.....in my elimination round the question was to convert the binary tree to double linked list....I gave 2 answers using stack and queue and array of structures..... But coulkdnt give inplace answer...

Applied through employee referral. Got email from HR recruiter. Two phone screens which were fairly easy and then five onsite interviews; hard enough to sweat. Questions were focused on algorithms. Prepare everything: career cup, PIE. Don't really know what they expect. Phone screen 1: Basics of data structures like stacks, queues, hash tables. Code: check whether a given string is palindrome or not. Follow up: Find all substrings in a string that are palindromic. Phone screen 2: concepts of operating systems: deadlock, threads v processes Code: A number between [0-N] is missing in an array of [0-N-1]. Find the missing number. Design: Poker game.