Topological Sorting Using DFS

Problem statement

In the field of computer science, a topological sort or topological ordering of a directed graph is a linear ordering of its vertices such that for every directed edge (u, v) from vertex u to vertex v, u comes before v in the ordering. For instance, the vertices of the graph may represent tasks to be performed, and the edges may represent constraints that one task must be performed before another. In this application, a topological ordering is just a valid sequence for the tasks. A topological ordering is ...