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bridge.xyz·Software Engineer·Technical Phone Screen·Intermediate

Intermediate
May 2026

Summary

Got a technical phone screen for a Software Engineer role at Bridge.Xyz. Single coding question, file path normalization, felt straightforward on the surface but there are enough edge cases to trip you up if you're not careful.

Questions Asked (1)

Q1

Given an absolute Unix-style file path as a string, implement a function that returns its canonical normalized form. Handle dots, double dots, consecutive slashes, and trailing slashes correctly.

Algorithms & Data StructuresTechnical Trade-offs
Author's notes

Stack-based approach is the right call here.

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AI HintsAI Generated

Suggested Approach

Clarify the rules for canonicalization (absolute path, no trailing slash except root, no '.' or '..', no consecutive slashes). Then propose a stack-based solution: split the path by '/', process each component, and join the result. Walk through edge cases like root, multiple slashes, and '..' at root.

Pro tip: Mention that you'd use a stack (or deque) to handle '..' efficiently, and that you'd avoid regex for clarity and performance. Also, discuss trade-offs: in-place vs. new string, and handling of Unicode or special characters if relevant.

1. Clarify requirements and edge cases

Confirm that the path is absolute, and define canonical form: starts with '/', no trailing slash (except root), no '.' or '..', no consecutive slashes. Ask about empty input or invalid paths.

2. Choose data structure and algorithm

Use a stack to store valid directory names. Split the path by '/', iterate over components, and for each: ignore empty or '.', pop for '..' if stack not empty, else push valid names.

3. Implement and handle edge cases

Build the result by joining stack elements with '/' and prefixing with '/'. Handle root case (empty stack) by returning '/'. Ensure no trailing slash unless root.

4. Test with examples and discuss complexity

Walk through examples like '/a/./b/../../c/' -> '/c', '/../' -> '/', '/home//foo/' -> '/home/foo'. State time and space complexity: O(n) time, O(n) space.

5. Discuss trade-offs and optimizations

Mention alternative approaches (e.g., using split and filter, or in-place modification) and their trade-offs. Consider if the input can be modified in-place to save space.

Key Points to Mention

  • Stack-based approach for handling '..' and building the canonical path.
  • Edge cases: root path, multiple slashes, trailing slash, '..' at root.
  • Time and space complexity: O(n) time, O(n) space.
  • Avoiding regex for simplicity and performance.
  • Handling of empty components from consecutive slashes.
  • Clarifying assumptions about input validity and absolute path.

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