This took me a minute to even parse correctly.
Use depth-first search (DFS) with a temporary mark to detect cycles and a permanent mark to avoid revisiting nodes, building the order in post-order. Handle missing packages by treating them as leaves or raising an error, and deduplicate dependencies by using a set. Return the reversed post-order list as the build order.
Pro tip: Mention that you would cache results of get_dependencies to avoid repeated API calls, and discuss how to handle cycles by either breaking them or reporting an error, depending on requirements.
Ask about expected behavior for cycles (error vs. break), missing packages (ignore vs. error), and whether the build order should include the target package itself.
Use DFS with three states: unvisited, visiting (in current path), and visited (fully processed). This detects cycles and avoids duplicate work.
For each package, mark it as visiting, recursively process its dependencies (from get_dependencies), then mark it as visited and add it to the result list. If a dependency is already visiting, a cycle is detected.
If get_dependencies returns a package that doesn't exist, either treat it as a leaf or raise an error. Use a set to deduplicate dependencies before processing.
After DFS completes, reverse the result list to get a valid topological order where dependencies come before dependents.
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.