Expedia SDE-3 Gurgaon — coding, trees, HLD recommendations; reject

I applied in expedia Gurgaon via referral. Got a call from the recruiter after about a week. Since I was also a former employee of Expedia, they conducted a background check that took around 15 days before moving forward.

Round 1 | Coding, Problem Solving
Questions about previous projects, followups on distributed systems and scaling. 1 LC medium-hard question on DP (solved). Laptop hung midway, lost ~10 minutes, interviewer patient and skipped the second question.

Round 2 | Coding, DS/Algo
2 LC medium questions on trees and stack (solved both). Interviewer asked follow ups and asked me to modify the code, which I did optimally.

Round 3 | Design HLD
Design a book recommendation system:

• Users could create posts (book reviews, recommendations) with likes and comments.
• Publishers could also create posts about book recommendations.
• Users get book recommendations from publishers as well as the system.
• Users could follow each other.
  Discussion around DB design for posts/likes/comments and aggregation of likes. Interviewer was more interested in system-generated recommendations: scraping user/publisher posts to score books per genre and users' interest per genre, and a recommender service creating posts for a user's timeline. This round didn't go well.

Round 4 | Technical Acumen, Overall Fitment
Previous projects, mentoring experience, most challenging project, a time I displayed leadership.

Received the rejection call after a week.