Explanation

- **Topological Sort** is used to order the vertices of a **directed acyclic graph (DAG)** such that for every directed edge `(u, v)`, vertex `u` appears before `v`.

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Steps:
- Find all vertices with no incoming edges (in-degree of 0) and add them to a queue.
- Repeatedly remove a vertex from the queue, add it to the topological order, and reduce the in-degree of its neighbors.
- Repeat until all vertices are processed.
Time Complexity:
- O(V + E), where V is the number of vertices and E is the number of edges.