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Whatnot Interview Question Bank

Whatnot is a live-stream shopping marketplace, and its engineering loop reflects that: engineers are expected to think like users of the app, with product sense assessed alongside coding and system design. Coding screens favor short, practical problems where finishing and testing the follow-ups matters more than algorithmic depth.

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Last updated 2026/10/13

Coding problems

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User Journey Paths: Action-Log Prefix Tree

Given (user_id, time, action) logs, rebuild each user's time-ordered journey, insert every journey into a trie that counts distinct users per path prefix, and print the trie as an indented tree. Follow-up: logs arrive as a stream. Recruiters may announce two LC mediums, but interviewers often swap in this problem as the only question.

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