Microsoft Software Developer - Internship interview questions

I contacted a recruiter, applied online, then was contacted to schedule a phone interview. They asked questions about my work experience and personal projects such as "What algorithms and data structures did you use in this project and why?" and "What was the biggest challenge for that project and how did you overcome it?". Then they asked various questions to see how you think like, "How would you explain recursion to a child?". A few weeks after this I was contacted by the recruiter saying that they liked me and wanted to move on to an in-person, on-site interview, but there weren't enough available interview slots. So, they put me on a wait list essentially.