Hex encode decode
Write hex_encode and hex_decode to convert between hex strings and integer byte values.
ROT13 Transform
Implement ROT13, a letter substitution cipher that rotates the alphabet by 13 positions.
Caesar Cipher Decrypt
Implement a function that decrypts a Caesar cipher by shifting letters back by a given number.
Simplify Path
Implement a function that simplifies a Unix-style absolute file path to its canonical form.
Basic Calculator III
Implement a recursive descent parser to evaluate a fully parenthesized arithmetic expression with +, -, *, / and parentheses.
Minimum Remove Valid Parentheses
Given a string with parentheses and letters, remove the fewest parentheses to make it valid.
Remove Duplicate Letters
Implement a function that removes duplicate characters from a string while preserving the order of their first occurrence.
Custom Sort String
Given a string s and an order string, reorder s so that characters that appear in order come first in that order, and all other characters are appended in stable original order.
Change directory manager
Implement a function that processes `cd` commands and returns the resulting absolute path.
Parse URL components
Write parse_url that splits a URL into its standard components with defaults for missing parts.
Parse HTTP Status Line
Write a function that parses a well-formed HTTP status line into its three components.
Parse key-value lines
Parse structured key-value lines into a dictionary with support for quoted values and escaped characters.
Parse markdown headers
Write a function that parses markdown headers and returns their levels and texts.
Parse bullet list
Parse a markdown-style bullet list and return the list of item texts, stripping bullet markers and trimming surrounding whitespace.
Parse numbered list
Take a string containing a numbered list and return a clean list of the item texts.
Decode base64 string
Write a function that decodes a base64 string to its original UTF-8 text without using the base64 module.
Parse Version SemVer
Write a function that parses a semantic version string into its numeric components.
Compare Version Strings
Given two version strings, compare them numerically by splitting on dots and ignoring leading zeros.
Parse path segments
Implement a function that parses a path string into clean segments, ignoring slashes, empty parts, and dot segments.
Parse coordinate pairs
Parse a string of coordinate pairs into a list of coordinate lists.
Parse range notation
Parse a comma-separated list of ranges and individual numbers, expanding each range into its full sequence.
Parse Boolean Strings
Implement a function that parses a boolean string into a Python bool, handling True/False/Yes/No/1/0 case-insensitively.
User Friendly Message
Given a raw user input, format it into a single clean sentence with proper sentence case and trimming.
Find repeated words
Return a lowercase list of unique words that appear more than once across a given text, ignoring case.
Showing 97–120 of 219 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.