Amazon Software Engineer interview questions

Applied Online; contacted for a telephone interview of about 45 min. Three questions: Hash Table, Having n log files containing IP address find an algorithm to find unique IPs, Sum subsetin array of integers.

An on-compus interview opportunity, two round involving four interviews, each one was 45 mins. The first round is easy, one interview, just some basic DP, recursion problems and simple data structures. The second round is harder, three interviews, ask questions about system scalability, how to implement a maze and a data structure to find the medium of a stream int.