Duration Human Readable
Write a function that turns a number of seconds into a human-readable duration like '2 hours, 1 minute'.
Schedule conflict check
Write a function that takes a list of time intervals and returns True if any two overlap.
Julian Day Number Converter
Implement two functions to convert between Gregorian calendar dates and Julian Day Numbers using a standard formula.
Month End Date
Implement a function that returns the last day of the month for a given year and month.
Easter Date Calculator
Implement a function that returns the date of Easter Sunday for a given year using the Gregorian computus algorithm.
Base64 Encode/Decode
Implement two functions to encode and decode Base64 strings using the standard alphabet and padding.
Generate CSV row
Implement a function that converts a list of values into a single CSV row with correct quoting and escaping.
Flatten nested JSON
Write a function that flattens nested JSON objects into a flat dictionary with dot-separated keys, handling lists and empty objects.
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.
Inner Join Two Tables
Write a function that inner joins two lists of dictionaries on a common key and returns the combined rows.
Create Table Schema
Write a function that creates a SQLite table with a given name and columns, and returns the resulting schema as a list of column definitions.
Nth Highest Salary
Write a Python function using SQLite to return the Nth highest distinct salary from an employee table.
Cumulative Sum SQL
Write a SQL query to compute cumulative sales totals per product ordered by sale date.
Select All Users
Write a function that connects to an in-memory SQLite database and returns all users as a list of lists.
Add column alter
Write a function that connects to an in-memory SQLite database, creates a table, inserts rows, and adds a new column with ALTER TABLE.
SHA256 Hash String
Write a function that returns the SHA256 hexadecimal digest of a given string.
Compute SHA-1 Hash String
Write a function that returns the SHA-1 hash of a string as a 40-character hex string.
Constant Time Compare
Write a function that compares two strings without leaking length or content via timing.
Verify HMAC signature
Implement a function that verifies an HMAC-SHA256 signature for a message and key.
Showing 337–360 of 365 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.