## Problem Implement bidirectional conversion between nested JSON and a flat dot-notation key-value format. Nested keys are joined with `.`; array indices use bracket notation. ```python def flatten_json(obj: dict, prefix: str = "") -> dict[str, str]: # {"a": {"b": 1}, "c": [2, 3]} -> {"a.b": "1", "c[0]": "2", "c[1]": "3"} pass def unflatten_json(flat: dict[str, str]) -> dict: # Reverse of flatten_json pass ``` **Example:** ``` flatten_json({"user": {"name": "Alice", "scores": [10, 20]}}) -> {"user.name": "Alice", "user.scores[0]": "10", "user.scores[1]": "20"} unflatten_json({"user.name": "Alice", "user.scores[0]": "10", "user.scores[1]": "20"}) -> {"user": {"name": "Alice", "scores": [10, 20]}} ``` ## Follow-ups 1. How do you handle key collisions when a path could be both a leaf and a subtree? 2. How do you distinguish between a string value "10" and an integer 10 in the flat format? 3. How would you extend this to support mixed arrays (arrays containing both objects and primitives)? 4. What is the maximum nesting depth your solution supports before hitting Python's recursion limit?

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JSON Conversion: Convert Between JSON and a Custom Flat Key-Value Notation

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Problem Implement bidirectional conversion between nested JSON and a flat dot-notation key-value format. Nested keys are joined with .; array indices use bracket notation. Example: Follow-ups How do you handle key collisions when a path could be both a leaf and a subtree? How do you distinguish between a string value "10" and an integer 10 in the flat format? How would you extend this to support mixed arrays (arrays containing both objects and primitives)? What is the maximum nesting depth your…

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This is a candidate experience report from a nextdoor interview during the phone round.

It covers the following topics: Strings, Phone, Recursion, Coding, Arrays .

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JSON Conversion: Convert Between JSON and a Custom Flat Key-Value Notation

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