X Software Engineer - Internship interview questions

I applied online, they sent me an online coding interview. Simple String and data structure questions. After a month I came to SF for another round of interview, there were some behavioral questions and some more data structure.

Given a hackerrank challenges to solve and after that scheduled a phone interview with algorithm questions. Reject after the phone interview but the recruiter was really helpful and questions level was medium. In the Phone interview I didn't understand some points and didn't well.