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467 challenges 330 easy 120 medium 17 hard

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Graphs & Graph Algorithms easy

Cycle Detection in a Directed Graph

Use DFS with a recursion stack to detect cycles in a directed graph.

graph dfs cycle

Graphs & Graph Algorithms easy

Cycle Detection in Undirected Graph

Write a function that detects if an undirected graph contains a cycle.

graph dfs cycle-detection

Graphs & Graph Algorithms medium

Course Schedule Can Finish

Given numCourses and prerequisites, return whether all courses can be finished without cyclic dependencies.

graph cycle topological

Graphs & Graph Algorithms medium

Graph Valid Tree

Determine if n nodes and an edge list form a valid tree (connected and acyclic).

Showing 4 challenges · Graphs & Graph Algorithms

Graphs & Graph Algorithms — Python coding challenges

What you will find here

This page lists graphs & graph algorithms challenges — real Python problems you solve in the browser IDE with instant test feedback. Each challenge includes a clear brief, starter code, and automated checks.

Challenges vs tutorials and quizzes

Challenges test what you can build under constraints. For guided teaching, use our Python tutorials. For quick checks, try quizzes or copy snippets from code samples.