## Problem Given two hashmaps (dicts) A and B, compute their difference report: keys only in A, keys only in B, keys in both but with different values, and keys in both with identical values. ```python from dataclasses import dataclass from typing import Any @dataclass class DiffReport: only_in_a: dict # key -> A[key] only_in_b: dict # key -> B[key] changed: dict # key -> (A[key], B[key]) unchanged: dict # key -> value def dict_diff(a: dict, b: dict) -> DiffReport: pass ``` **Example:** ``` a = {"x": 1, "y": 2, "z": 3} b = {"y": 99, "z": 3, "w": 4} dict_diff(a, b) -> DiffReport( only_in_a={"x": 1}, only_in_b={"w": 4}, changed={"y": (2, 99)}, unchanged={"z": 3} ) ``` ## Follow-ups 1. How do you handle nested dicts — would you diff recursively? 2. What equality check do you use for values that may be lists or objects? 3. How would you serialize the DiffReport as a human-readable patch format? 4. How would you apply a DiffReport to transform dict A into dict B?

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Hashmap Difference: Compute the Symmetric Difference Between Two Hashmaps

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Problem Given two hashmaps (dicts) A and B, compute their difference report: keys only in A, keys only in B, keys in both but with different values, and keys in both with identical values. Example: Follow-ups How do you handle nested dicts — would you diff recursively? What equality check do you use for values that may be lists or objects? How would you serialize the DiffReport as a human-readable patch format? How would you apply a DiffReport to transform dict A into dict B?

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

It covers the following topics: Coding, Phone, Hash Table .

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Hashmap Difference: Compute the Symmetric Difference Between Two Hashmaps

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