Huijing demonstrated a solid grasp of distributed system design principles and communicated her thought process clearly throughout the session. Her proactive alignment with the interviewer and structured reasoning highlighted thoughtful planning and awareness of system trade-offs.

Areas of strength included:

• Clear identification and articulation of both functional and non-functional requirements
  
  
• Effective use of interviewer alignment to verify assumptions before progressing
  
  
• Consideration of pagination strategies for Top-K API design
  
  
• High-level architecture proposal including indexing strategy and sharding discussion
  
  
• Awareness of end-to-end latency, with ideas like pre-computation and caching
  
  
• Thoughtful data pipeline discussions (micro-batch vs streaming) for aggregation
  
  
• Good reasoning around sharding trade-offs (by score vs. by user_id)
  
  
• Consideration of fault tolerance strategies in Redis (e.g., Redis Cluster, snapshot checkpoints)
  
  

Areas for improvement:

• When discussing system scale, consider both user volume and event volume (e.g., 1M+ events/sec) to cover burst scenarios
  
  
• Explicitly define core entities like Leaderboard, which is central to the system
  
  
• Clarify technical terms like sorted sets and skip lists during component discussions
  
  

Suggestions & Discussions:

• Consider adding thoughts on how to handle duplicate submissions to the leaderboard and the implications on consistency, fairness, and ranking logic