Amazon Software Development Engineer - Intern interview questions

Applied online and got a email from recruiter after around 3 weeks. Scheduled a interview after 4 days. There were 2 back to back phone interviews. Both the interviewers were very friendly. They initially asked questions on my background and asked to explain any of my project. Then they started asking technical questions along with algorithms/data structure. I had to explain the logic and after that I had to speak out the code explaining what I am doing. They always asked my to optimize the code to reduce time/space complexity. Overall I could answer all the questions they asked.