Time Slot Generator
Generate a list of time slots of a specified duration within a start and end time.
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 YAML-like dict
Parse a simple YAML-like text with indentation into a nested dictionary.
Flatten nested JSON
Write a function that flattens nested JSON objects into a flat dictionary with dot-separated keys, handling lists and empty objects.
Unflatten JSON dict
Given a flat dictionary with keys like 'a.b.c', reconstruct the nested dictionary where each dotted segment becomes a nested level.
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.
Serialize dict to TOML-like
Convert nested Python dicts into a simplified TOML-like string with sorted keys, type-aware formatting, and flat table sections.
Update Row by ID
Given a list of CSV rows and target ID, replace the first matching row's value.
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.
Index Creation Query
Create an in-memory SQLite database, execute CREATE INDEX statements, and return the resulting index metadata rows.
Second highest salary
Given an employees table, write a SQL query that returns the second highest distinct salary, or NULL if it doesn't exist.
Nth Highest Salary
Write a Python function using SQLite to return the Nth highest distinct salary from an employee table.
Customers Never Order
Given Customers and Orders tables, return the names of customers with no orders, sorted alphabetically, or None if all have ordered.
Cumulative Sum SQL
Write a SQL query to compute cumulative sales totals per product ordered by sale date.
Showing 865–888 of 925 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.