## Problem Design a backend API for managing hierarchical data (e.g., org charts, category trees). Each node has an `id`, `name`, `parent_id`, and optional `metadata`. Implement these endpoints: ``` POST /nodes - create a node (specify parent_id or null for root) GET /nodes/:id - get a node and its direct children GET /nodes/:id/subtree - get a node and all descendants PUT /nodes/:id - update name or metadata DELETE /nodes/:id - delete node and all descendants PUT /nodes/:id/move - move subtree to a new parent ``` ## Example ``` POST /nodes {"name": "Engineering", "parent_id": null} -> {"id": "1"} POST /nodes {"name": "Backend", "parent_id": "1"} -> {"id": "2"} POST /nodes {"name": "Frontend", "parent_id": "1"} -> {"id": "3"} GET /nodes/1/subtree -> {"id":"1", "children": [{"id":"2"}, {"id":"3"}]} PUT /nodes/2/move {"new_parent_id": "3"} -> Backend becomes child of Frontend ``` ## Follow-ups 1. What database representation (adjacency list, nested sets, closure table, path enumeration) fits best for this use case? 2. How do you implement `GET /subtree` efficiently without loading the whole table? 3. How do you prevent a `move` operation from creating a cycle?

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Tree Backend: Design a REST API for Managing a Hierarchical Tree Structure

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Problem Design a backend API for managing hierarchical data (e.g., org charts, category trees). Each node has an id, name, parent_id, and optional metadata. Implement these endpoints: Example Follow-ups What database representation (adjacency list, nested sets, closure table, path enumeration) fits best for this use case? How do you implement GET /subtree efficiently without loading the whole table? How do you prevent a move operation from creating a cycle?

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This is a reported interview question from a jane street interview for a backend role during the phone round.

It covers the following topics: Coding, Sql, Phone, Onsite .

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Tree Backend: Design a REST API for Managing a Hierarchical Tree Structure

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