← Airbnb Interview Insights

Airbnb·Software Engineer·Technical Phone Screen·Intermediate

Intermediate
Apr 2026

Summary

Airbnb software engineer screen, one coding question about URL parsing. Pretty straightforward on the surface but the follow-up discussion went in a few directions I wasn't fully prepared for.

Questions Asked (1)

Q1

Given a URL string, parse its query string and return all the query parameters as a key-value dictionary. Handle edge cases like keys with no values, URLs with no query string at all, and discuss how you'd deal with percent-encoding and repeated keys.

Algorithms & Data StructuresTechnical Trade-offsAPI & Integrations
Author's notes

The base implementation wasn't bad.

Create a free account to read the full note

AI HintsAI Generated

Suggested Approach

Start by clarifying requirements and edge cases, then outline a step-by-step parsing algorithm. Discuss trade-offs for handling percent-encoding and repeated keys, and provide a clean code implementation with tests.

Pro tip: Mention that you'd use built-in URL parsing libraries when available (e.g., urllib.parse in Python, URLSearchParams in JavaScript) to avoid reinventing the wheel, but be prepared to implement manually if asked.

1. Clarify requirements and edge cases

Ask about expected input format, handling of missing values, repeated keys, and encoding. Confirm the desired output structure (e.g., dict with string or list values).

2. Outline parsing algorithm

Describe splitting the URL at '?', then splitting by '&', then each pair by '='. Handle cases where '=' is missing (key with empty value) and empty query string.

3. Address percent-encoding and repeated keys

Explain decoding percent-encoded characters (e.g., %20 to space) and how to handle repeated keys: either last value wins, first value wins, or collect into a list. Discuss trade-offs.

4. Implement and test

Write clean code with helper functions, and walk through test cases: normal URL, no query string, key without value, repeated keys, encoded characters.

Key Points to Mention

  • Use built-in URL parsing libraries when possible for robustness and security.
  • Percent-encoding: decode both keys and values using appropriate functions (e.g., decodeURIComponent).
  • Repeated keys: decide on a strategy (list, last-wins, first-wins) and justify based on use case.
  • Edge cases: empty query string, keys without '=', empty values, and malformed pairs.
  • Security: be aware of potential injection attacks and validate/sanitize inputs.
  • Time and space complexity: O(n) time, O(n) space for the dictionary.

AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.