Build a Top-Three Referral Leaderboard from Chronological Events
Company: Robinhood
Role: Software Engineer
Category: Coding & Algorithms
Difficulty: medium
Interview Round: Onsite
Overview: Build a referral leaderboard from chronological referrer and referred-user arrays, counting every direct and downstream referral. The prompt returns the top three eligible users with deterministic count and username ordering, matching a DFS-and-memo solution over the referral forest.
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