delivery.com Software Engineer interview questions

was spoken with over the phone and then brought in 2 times to meet the team. Was asked many technical questions such as to design a database schema for a board game and about tree structures. As well, the interviewers wanted to genuinely know if I wanted to work here, to ensure that the fit is correct. There was a php component to the interview and a java component since the site is built on both. The java component was based around core java. What is a Set, what is a hashmap, the internals of hashmap etc.