Practice Arena

Python Coding
Challenges

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

819 challenges 506 easy 280 medium 33 hard

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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

Data Structures & Algorithms medium

Decode Ways

Count the number of ways to decode a numeric string into letters using the mapping A=1 to Z=26.

dynamic programming strings counting

Stacks & Queues medium

Decode String Stack

Decode a compressed string with repeated substrings like '3[a2[c]]' to 'accaccacc' using a stack-based approach.

stacks string parsing

Stacks & Queues medium

Decode Nested String

Implement a function that decodes a string with nested encoding patterns.

stack string parsing

Data Formats & Parsing medium

Base64 Encode/Decode

Implement two functions to encode and decode Base64 strings using the standard alphabet and padding.

base64 encoding string

Data Formats & Parsing medium

Base64 Encode Decode

Implement Base64 encoding and decoding functions that handle padding and all standard characters.

base64 encoding decoding

Showing 5 challenges · medium

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.