[Graph BFS/DFS] Course Schedule II

[sudosf]

Problem

Given n courses and prerequisites, return a valid ordering of courses to finish all of them. Return empty array if impossible.

References

• LeetCode: https://leetcode.com/problems/course-schedule-ii/
• GFG: https://www.geeksforgeeks.org/problems/topological-sort/1
• Sheet: https://www.risingbrain.org/sheet#graph (BFS/DFS section)
• Parent: Pattern: Graph - BFS and DFS Traversals #122

Difficulty

🟡 Medium

Companies

Amazon, Microsoft, PhonePe

Notes

Language: Java
Topological sort returning the actual order. Kahn's algorithm (BFS with in-degree) naturally produces the order. DFS approach reverses the finish order.