TikTok Interview Experience (My Third TikTok Interview Experience)

Round 1: HR Interview
This round had no technical questions. It mainly focused on understanding my personal background, project experiences, interest in the position, and visa status. Overall, it was quite relaxed and served as an initial screening stage.

Round 2: Hiring Manager Interview
This round officially began the technical assessment.
Key questions included:

• Describe the models used in the Candidate Generator of a recommendation system, explain the model principles and time complexity.
• Introduce the Ranker model in the recommendation system and its complexity analysis.
• Scenario question: If there are new users or new items in the system now, how to help them quickly resolve the cold start problem?
• Finally, there was a medium-difficulty coding question related to recommendation systems. I was required to write a bug-free version within a limited time. It ran successfully, and I performed solidly in the follow-up discussions.

Round 3: Head/Department Lead Interview
This round was hosted by the department head and was a high-intensity technical interview.
In-depth questions about the models used in my chatbot project, including mathematical derivation details.
Required to fully describe the recommendation system pipeline, with a focus on feature acquisition and design.
The coding part was a hard-difficulty dynamic programming question, to be completed within 15 minutes.