LeetCode Pattern: 18 Tips & Strategies for Solving Topological Sort Problems (Including 10 Classic Problems & Solutions)

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Topological sorting is an ordering of the vertices in a directed graph such that for every directed edge (u, v), vertex u comes before vertex v in the ordering. Here are tips and strategies for solving problems involving topological sorting:

1. Understand the Problem:

• Clearly understand the problem statement and the requirement for a topological order.
• Topological sorting is an ordering of the nodes (or vertices) in a directed acyclic graph (DAG) such that for every directed edge (u, v), node u comes before node v in the ordering. In other words, it’s a linear ordering of the nodes that respects the partial order imposed by the directed edges.

1.1 Indicators of Topological Sorting:

i. Directed Acyclic Graph (DAG):

• Problems that involve directed graphs where edges have a clear direction (one-way) and there are no cycles (DAG) often require topological sorting.
• Look for phrases like “directed graph,” “dependencies,” or “tasks with prerequisites.”

ii. Dependency Resolution:

• Topological sorting is…