The base version is manageable if you've seen the LeetCode problem before, but the Set and Delete operations with validation rules added a lot more edge cases than I expected.
Clarify requirements and constraints first, then design a tree-based structure (e.g., trie) with nodes representing files/directories. Discuss operations with validation, edge cases, and trade-offs between simplicity and scalability.
Pro tip: Explicitly discuss how you would handle concurrent access and atomicity, as DoorDash's systems require high reliability under load. Also, mention that you'd start with a simple in-memory solution and then scale to distributed storage if needed.
Ask about expected scale, path format, value types, and whether directories are implicit or explicit. Confirm if operations should be atomic and thread-safe.
Propose a trie (prefix tree) where each node represents a path component and stores a value if it's a file. Alternatively, use a hash map with full paths as keys for simplicity.
For each operation, specify validation rules: e.g., Create fails if path exists or parent missing; Get fails if path doesn't exist or is a directory; Set fails if path doesn't exist; Delete fails if path doesn't exist or is non-empty directory.
Compare trie vs. hash map in terms of time/space complexity and operations like listing directory contents. Mention potential extensions: permissions, versioning, distributed storage.
Explain how to handle concurrent access (e.g., locks, transactions) and how the design could scale to distributed systems (e.g., sharding by path).
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.