Three separate correctness conditions and I had to untangle which bugs corresponded to which.
Start by clarifying the requirements and edge cases, then outline a systematic approach: parse the config, build a dependency graph, detect cycles, and perform a DFS/BFS to check eligibility and dependencies for each requested feature. Finally, discuss how you would test the solution and handle potential issues like missing features or conflicting dependencies.
Pro tip: Emphasize the importance of cycle detection and transitive dependency resolution; mention that you would use a topological sort or DFS with visited states to avoid infinite loops and ensure all dependencies are checked efficiently.
Ask questions to understand the exact constraints: Are dependencies only direct or transitive? What if a requested feature is already pre-enabled? How should missing features be handled? What about multiple users or batch requests?
Propose representing features as nodes in a directed graph, with edges from a feature to its dependencies. Use a map for feature definitions and a set for pre-enabled features. Outline a DFS-based approach to check eligibility and dependencies, with cycle detection.
Write pseudocode or explain the steps: For each requested feature, check country and OS restrictions; then recursively check all dependencies, ensuring they are either pre-enabled or also requested and eligible. Use a visited set to detect cycles and avoid redundant checks.
Discuss how to handle missing features, cycles, and unsatisfied dependencies. Decide whether to fail the entire request or grant partially. Explain how to report errors clearly.
Outline test cases: simple grants, country/OS mismatches, missing dependencies, cycles, and pre-enabled features. Suggest unit tests and possibly a brute-force comparison for small cases.
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.