Build Order for a Target Package

Return the Complete Build Order for a Target Package Given package dependency relations and a target package name x, return the complete build order required to build x. A relation A B means that package A depends on package B to be built. The result must contain only x, its direct dependencies, and its transitive dependencies. Every package must appear after all of its dependencies. If a cyclic dependency is reachable from x, the build cannot be completed; return an empty list. Use DFS and detect cycles with these states: visiting: the package is on the current DFS path; visited: the package and all of its dependencies have been fully processed. Input Format (for this problem) First line: integer n, the number of dependency relations. Next n lines: package dependency, meaning package depends on dependency. Final line: target package name x. Output Format If acyclic: print one valid build order with package names separated by spaces. If cyclic: print an empty line. Example Input: 5 web api web frontend api database frontend shared-ui shared-ui assets web Output: database api assets shared-ui frontend web Constraints 1 <= n <= 2 * 10^5 Let the target-reachable subgraph contain V packages and E dependency edges. Example Input 5 web api web frontend api database frontend shared-ui shared-ui assets web Output database api assets shared-ui frontend web