Hint 1 — locked

Hint 2 — locked

Hint 3 — locked

Problem

Build a real-time leaderboard for an online game. Players submit scores after each match and can instantly see the global top-100 and their own rank. The leaderboard must update in real time as scores change and persist results across server restarts.

Functional Requirements

• Submit a player score after each match
• Query the top-N players (e.g. top 100) with ranks
• Query a specific player's current rank and score
• Scores update in real time (< 1 second propagation)
• Leaderboard persists across restarts

Non-Functional

• 10M active players, 1M score submissions per hour
• Rank queries served in < 10 ms
• Eventually consistent is acceptable for rank display
• Durable — no score loss if a server crashes