Hex encode decode
Write hex_encode and hex_decode to convert between hex strings and integer byte values.
Decode base64 string
Write a function that decodes a base64 string to its original UTF-8 text without using the base64 module.
Decode Ways
Count the number of ways to decode a numeric string into letters using the mapping A=1 to Z=26.
Gray Code Decode
Implement gray_decode(n) that converts an n-bit Gray code integer back to its standard binary value using XOR accumulation.
Decode String Stack
Decode a compressed string with repeated substrings like '3[a2[c]]' to 'accaccacc' using a stack-based approach.
Decode Nested String
Implement a function that decodes a string with nested encoding patterns.
Base64 Encode/Decode
Implement two functions to encode and decode Base64 strings using the standard alphabet and padding.
Base64 Encode Decode
Implement Base64 encoding and decoding functions that handle padding and all standard characters.
Showing 8 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.