Reentrant Lock Manager
Implement a ReentrantLock class with acquire, release, locked, owner, and helper functions that test thread-safety with real threads.
Suppress Specific Exceptions
Implement a custom context manager that suppresses specified exception types within its block.
Open the Lock BFS
Implement a BFS solution to find the minimum number of turns needed to open a 4-wheel lock, avoiding a set of deadends.
Android unlock patterns
Count the number of valid Android unlock patterns of a given length using a 3x3 grid with adjacency constraints.
Spiral Matrix Order
Given a 2D matrix, return all elements in clockwise spiral order starting from the top-left.
Spiral Matrix Traversal
Implement a function that returns the elements of a 2D matrix in clockwise spiral order.
Matrix Block Sum
Given a 2D matrix and a block size, compute the sum of each block centered at every cell.
Rotate Matrix Layers
Given a square matrix, rotate each concentric layer 90 degrees clockwise.
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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.