Practice Arena

Python Coding
Challenges

Write real Python in the browser. Instant feedback. From beginner to expert.

925 challenges 556 easy 323 medium 46 hard

All Easy Medium Hard

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

Dicts & Sets easy

Keys Sorted by Value Descending

Given a dictionary mapping strings to integers, return a list of keys sorted by value descending, and when values tie, alphabetically ascending.

sorting dictionaries ordering

OOP & Classes easy

Dataclass with slots

Implement a slotted frozen dataclass representing a 2D point with total ordering.

dataclass slots immutability

Data Structures & Algorithms hard

Topological sort (Kahn)

Return a valid topological ordering of tasks, or [] if a cycle exists.

graph BFS topological-sort

Graphs & Graph Algorithms medium

Topological Sort via DFS

Return a deterministic topological ordering of nodes in a directed acyclic graph using DFS, or an empty list if a cycle exists.

topological-sort dfs graph

Graphs & Graph Algorithms medium

Course Schedule Ordering

Determine a valid sequence to complete all courses respecting prerequisite constraints.

graph topological-sort bfs

Showing 1–5 of 5 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.