Pattern : It consists of 7 Tasks 4 DSA, 2 Debugging(coding based) and 1 MCQ

Bugfix

Given a list of service dependencies (service, depends_on) pairs, a service is blocked if it is part of a dependency cycle, or if it depends (directly or indirectly) on a service that is part of a cycle.

solution must return the sorted list of blocked services.

Rules: the same pair may appear more than once (duplicate edges — no effect on result). A service may depend on itself directly (a cycle of length 1). A service that never appears as the first element of any pair has no outgoing dependency and can never be part of a cycle. Output: blocked services, no duplicates, sorted ascending by byte value (plain ASCII order — "10" before "9", uppercase before lowercase).

Constraints: 0 ≤ length(dependencies) ≤ 2,000; each service name is 1–50 whitespace-free characters.

Bug found in given stub: In a DFS-based cycle detector using visiting/visited/cycleNodes sets, when a node is already fully processed (visited), the buggy code did return false unconditionally — losing the information that this node might already be part of a cycle. This causes nodes that depend on an already-processed cyclic node (via a different entry point) to be wrongly reported as not blocked.

Fix: if (visited.count(node)) return cycleNodes.count(node) > 0; instead of return false;