Classify triangle by sides
Write a function that classifies a triangle based on three side lengths.
Two Sum with Dict
Implement the classic Two Sum problem: return indices of two numbers that add up to a target using a dict.
Stack class
Implement a Stack class with push, pop, peek, is_empty, and size.
Matrix addition operator
Implement a Matrix class that supports + and * operators.
Event emitter basics
Implement an EventEmitter class with subscribe/emit/unsubscribe functionality.
Rectangle class
Implement a Rectangle class with properties, methods, and special methods for basic geometry and comparison.
Complex Number Class
Implement a Complex class supporting addition, subtraction, multiplication, division, equality, and string formatting.
Queue class (list-based)
Implement a Queue class with enqueue, dequeue, peek, is_empty, and is_full methods using a list.
Class Method Factory
Create a class method factory that dynamically adds methods to a class based on a mapping of names to behaviors.
Abstract Base Class
Create an abstract Shape class and implement Rectangle and Circle subclasses with area and perimeter.
Reentrant Lock Manager
Implement a ReentrantLock class with acquire, release, locked, owner, and helper functions that test thread-safety with real threads.
Union Find Class
Implement a UnionFind class with find and union operations supporting path compression and union by size.
2D Vector dataclass
Implement a Vector2D dataclass with +, -, scalar *, dot product, and magnitude.
Data pipeline
Implement a Pipeline class supporting pipe chaining with the | operator.
Validated descriptor
Implement a TypedField descriptor that raises TypeError if the value is not of the expected type.
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.
Context Manager Class
Implement a context manager class that measures execution time and sets duration, with None if an exception occurred.
File Open Context Manager
Create a class that acts as a context manager for opening a virtual file in memory.
Lookahead Validation
Write a regex-based function to check if a password meets length and character class requirements.
Levenshtein Distance
Implement the classic Levenshtein distance algorithm to measure string similarity.
Edit Distance (Levenshtein Distance)
Implement the classic edit distance algorithm to find the minimum number of single-character edits required to transform one string into another.
0/1 Knapsack
Implement the classic 0/1 Knapsack dynamic programming solution to maximize value under a weight capacity.
Egg Drop Puzzle
Given k eggs and n floors, compute the minimum number of attempts required in the worst case to find the highest safe floor.
Binary Search Tree Class
Build a BinarySearchTree class and a sequence runner that executes a list of operations.
Keys and Rooms
A classic graph traversal challenge: check if all rooms are reachable from room 0 using keys found in visited rooms.
Min Heap Class
Build a MinHeap class with push, pop, peek, and size methods that maintain a valid min-heap.
Showing 27 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.