Group by Department
Implement a function that groups a list of employee dictionaries by department, returning a dictionary keyed by department with lists of employee dictionaries.
Pivot sales by product
Write a function that pivots sales records into a dictionary keyed by product with monthly totals.
Stack class
Implement a Stack class with push, pop, peek, is_empty, and size.
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.
Queue class (list-based)
Implement a Queue class with enqueue, dequeue, peek, is_empty, and is_full methods using a list.
Abstract Base Class
Create an abstract Shape class and implement Rectangle and Circle subclasses with area and perimeter.
Deck of Cards Class
Implement a Deck class representing a standard 52-card deck with shuffle, deal, and len support.
Dataclass with slots
Implement a slotted frozen dataclass representing a 2D point with total ordering.
Playing card class
Design a PlayingCard class with suit, rank, color, and equality/comparison magic methods.
Count pairs with given difference
Count how many unordered pairs in a list have a given absolute difference using an efficient approach.
Previous Smaller Element
Find the nearest previous index with a smaller value for every element in an array.
Union Find Class
Implement a UnionFind class with find and union operations supporting path compression and union by size.
Delete Old Records
Filter a list of records by removing those with a date older than a given cutoff date.
Argsort Indices
Implement a function that returns the indices that would sort a list of integers, with ties broken by original order.
Employees earning more than manager
Given employee records with manager IDs, find those who earn more than their direct manager.
Default Argument Trap
Implement a function that safely accumulates items without the classic mutable default argument bug.
Range-like generator
Implement a custom generator that yields numbers like Python's range but with flexible bounds.
File Line Reader Generator
Implement a generator function that reads a file-like object and yields each non-empty line without loading the whole file into memory.
Zip Longest Fill
Create an iterator that yields lists from multiple iterables, padding with a fill value when lengths differ.
Graph DFS Generator
Implement a generator function that performs a depth-first traversal of a graph without recursion.
Context Manager Class
Implement a context manager class that measures execution time and sets duration, with None if an exception occurred.
Timer Context Manager
Implement a context manager that measures execution time of a with block and stores it.
Lock Context Manager
Implement a Lock class with acquire/release and context manager support.
Showing 49–72 of 110 challenges · easy
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.