Given `numCourses` and a `prerequisites` list of `[course, dependsOn]` pairs, implement `canFinish(numCourses, prerequisites)` returning whether all courses can be completed (the dependency graph has no cycle).
+ 1 hidden test run on Submit.
Kahn's topological sort finishes all courses only if there is no cycle. O(V + E) time.
Run your code to see results.