Word Search Matrix
Given a 2D board and a word, determine if the word can be formed by sequentially adjacent cells (horizontally or vertically), without reusing cells.
Regions Cut by Slashes
Given a grid of slashes, count the number of connected regions formed by the slashes and the grid borders.
Format date output
Parse ISO date strings and format them into a friendly US-style date output.
Duration Human Readable
Write a function that turns a number of seconds into a human-readable duration like '2 hours, 1 minute'.
Extract JSON-like numbers
Parse a simplified JSON-like string without using the json module and sum all numbers found in it.
Base64 Encode/Decode
Implement two functions to encode and decode Base64 strings using the standard alphabet and padding.
Protocol definition
Parse a simple wire protocol string into a structured dictionary.
Config Parser Reader
Parse a simple INI-style configuration text into a nested dictionary.
Generate CSV row
Implement a function that converts a list of values into a single CSV row with correct quoting and escaping.
Parse email header
Write a function that parses a raw email header string and returns sender, recipient, and subject.
Encode Base64 String
Write a function that encodes a UTF-8 string into a base64 string without using the base64 module.
Base64 Encode Decode
Implement Base64 encoding and decoding functions that handle padding and all standard characters.
Parse CSV Row
Implement a robust function that parses a single CSV line into a list of fields, handling double quotes and escaped quotes.
Parse Apache log line
Write a function that parses a single Apache access log line into a dictionary with IP, timestamp, request, status, and size.
Parse table rows
Implement a function that converts a simple text table into a list of dictionaries.
Constant Time Compare
Write a function that compares two strings without leaking length or content via timing.
XOR Cipher Encode
Implement the XOR cipher: encode a string by XORing each character with a key character.
Constant time compare
Write a function that compares two strings in constant time to avoid timing attacks.
Showing 145–162 of 162 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.