Euclidean Distance Matrix
Write a function to compute the Euclidean distance between every pair of points from two lists.
Logging Filter
Given a list of log entries, return those matching a given severity level and containing a keyword.
Argmax along axis
Write a function that returns index positions of the maximum values along rows or columns of a 2D list.
Remove Consecutive Duplicate Letters
Implement a function that removes consecutive duplicate letters from a string, keeping only one occurrence of each run.
Interleave Two Strings
Given two strings s1 and s2, return a new string that interleaves them character by character, starting with s1.
Count consonants
Write a function that counts the number of consonant letters in a string.
Remove Duplicates from String
Given a string, return a new string with each character that repeats consecutively reduced to a single occurrence.
Count Syllables (Simple)
Count syllables in a word by counting groups of consecutive vowels (a, e, i, o, u).
Expand compressed string
Implement a function that expands run-length encoded strings (e.g., 'a3b2' → 'aaabb').
Generate a Multiplication Table
Build a function that returns an n x n multiplication table as a list of lists.
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.
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.
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.
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.
Validation result object
Implement a ValidationResult class that tracks validation errors and can report validity.
Sieve of Eratosthenes
Implement the Sieve of Eratosthenes to return a sorted list of all primes up to a given integer n.
Prime Factorization
Return a sorted list of prime factors of a positive integer, including repeated factors.
Happy number check
Implement a function that returns True if a number is happy, False otherwise.
Showing 25–48 of 49 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.