Can all courses be finished given prerequisites?
Reported in Amazon interview loops. Topological sort and directed cycle detection interview staple.
Interview scenario
Context for Amazon candidates:
Each prerequisite pair means one course depends on another. Return whether all courses can be completed.
Model answer
Try answering aloud first
Cover trade-offs, structure, and a concrete example before revealing the baseline response.
How to frame this at Amazon: Connect your answer to measurable impact, clarity of thought, and trade-offs the team cares about. Below is a strong baseline response you can adapt with your own project examples.
Model courses as a directed graph and detect cycles. If a cycle exists, dependency order is impossible and answer is false.
Two standard approaches: DFS with recursion states (unvisited, visiting, visited) or Kahn algorithm using indegree queue. Kahn is iterative and easier to explain when interviewers ask for actual ordering too.
Complexity is O(V + E), where V is number of courses and E is prerequisites.
Discussion
Comments (0)
Share how this question came up in your loop, or add tips for others preparing.
Log in to comment on this question.