Classify triangle by sides
Write a function that classifies a triangle based on three side lengths.
Min-Max Scaler: Fit and Transform
Implement a MinMaxScaler class that normalizes numeric data to a given range using fit and transform methods.
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.
Design Twitter Feed
Implement a Twitter class with postTweet, getNewsFeed, follow, and unfollow methods.
Observer pattern lite
Implement a simple Subject class supporting subscribe, unsubscribe, and notify observers.
Deck of Cards Class
Implement a Deck class representing a standard 52-card deck with shuffle, deal, and len support.
String Representation Mixin
Implement a mixin class that provides generic __repr__ and __str__ based on instance attributes.
Dataclass with slots
Implement a slotted frozen dataclass representing a 2D point with total ordering.
Singleton Factory
Implement a factory class that returns a singleton instance per key.
Playing card class
Design a PlayingCard class with suit, rank, color, and equality/comparison magic methods.
Seat Manager Design
Implement a SeatManager class that supports reserving the smallest available seat and unreserving seats.
Union Find Class
Implement a UnionFind class with find and union operations supporting path compression and union by size.
Design Browser History
Implement a BrowserHistory class that supports visit, back, and forward navigation with step counts.
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.
Showing 1–24 of 48 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.