Cycle a List Once
Implement a function that rotates a list right by one position.
Garbage Collection Hint
Write a function that predicts when an object is garbage collected based on reference counting.
Topological sort (Kahn)
Return a valid topological ordering of tasks, or [] if a cycle exists.
Redundant Connection
Given a list of edges forming a tree plus one extra edge, return the edge that appears last in the input and creates a cycle.
Async Context Manager Lifecycle
Build an async context manager class that tracks acquisition and ensures cleanup.
Custom iterator class
Implement a custom iterator class that repeatedly yields elements from a list up to a given number of times.
Cycle Detection in a Directed Graph
Use DFS with a recursion stack to detect cycles in a directed graph.
Cycle Detection in Undirected Graph
Write a function that detects if an undirected graph contains a cycle.
Course Schedule Can Finish
Given numCourses and prerequisites, return whether all courses can be finished without cyclic dependencies.
Graph Valid Tree
Determine if n nodes and an edge list form a valid tree (connected and acyclic).
Showing 10 challenges
Guide: free Python coding challenges
Practice Python by solving problems
PythonSkillset challenges are hands-on coding exercises from beginner to advanced. Open a challenge, read the problem, write Python in the split-pane editor, and run tests with Pyodide — no install required.
How to use the arena
- Pick a category — basics, algorithms, strings, and more
- Open a challenge, read the statement, and edit the starter code
- Run tests, fix failures, then try a related quiz or tutorial lesson
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.