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Python Coding
Challenges

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875 challenges 536 easy 303 medium 36 hard

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All Python Basics Strings & Text Lists & Arrays Dicts & Sets Functions & Closures OOP & Classes Data Structures & Algorithms Advanced Python Iterators & Generators Decorators & Context Managers Error Handling & Exceptions Regular Expressions Math & Number Theory Bit Manipulation Dynamic Programming Trees & Binary Trees Graphs & Graph Algorithms Recursion & Backtracking Greedy Algorithms Binary Search Two Pointers & Sliding Window Stacks & Queues Heaps & Priority Queues Linked Lists Matrix & 2D Arrays Datetime & Time Calculations Data Formats & Parsing SQL & SQLite Numpy & Vectorized Computing Cryptography & Hashing

Lists & Arrays easy

Longest Run of Equal Values

Compute the length of the longest run (consecutive block) of equal elements in a list.

lists consecutive run-length

OOP & Classes medium

Reentrant Lock Manager

Implement a ReentrantLock class with acquire, release, locked, owner, and helper functions that test thread-safety with real threads.

threading locking reentrant

Decorators & Context Managers easy

Timer Context Manager

Implement a context manager that measures execution time of a with block and stores it.

context-manager timing measurement

Decorators & Context Managers easy

Suppress stderr manager

Implement a context manager that suppresses all output written to stderr during its block.

context-managers stderr redirect

Decorators & Context Managers easy

Lock Context Manager

Implement a Lock class with acquire/release and context manager support.

context-manager threading lock

Error Handling & Exceptions easy

Else on try block

Implement a function that uses try-except-else to safely divide two numbers and return a result or error description.

exception-handling try-except-else division

Error Handling & Exceptions medium

Suppress Specific Exceptions

Implement a custom context manager that suppresses specified exception types within its block.

context-manager exceptions suppress

Graphs & Graph Algorithms medium

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.

bfs strings graph

Graphs & Graph Algorithms medium

Android unlock patterns

Count the number of valid Android unlock patterns of a given length using a 3x3 grid with adjacency constraints.

graphs dfs backtracking

Matrix & 2D Arrays medium

Spiral Matrix Order

Given a 2D matrix, return all elements in clockwise spiral order starting from the top-left.

matrix spiral traversal

Matrix & 2D Arrays medium

Spiral Matrix Traversal

Implement a function that returns the elements of a 2D matrix in clockwise spiral order.

matrix traversal simulation

Matrix & 2D Arrays easy

Rotate Image 90 Degrees Clockwise

Rotate a square matrix 90 degrees clockwise and return the rotated matrix.

matrix rotation in-place

Matrix & 2D Arrays medium

Matrix Block Sum

Given a 2D matrix and a block size, compute the sum of each block centered at every cell.

matrix prefix-sum 2d-array

Matrix & 2D Arrays medium

Rotate Matrix Layers

Given a square matrix, rotate each concentric layer 90 degrees clockwise.

matrix rotation in-place

Showing 14 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.