Practice Arena

Python Coding
Challenges

Write real Python in the browser. Instant feedback. From beginner to expert.

925 challenges 556 easy 323 medium 46 hard

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All Python Basics Strings & Text Lists & Arrays Dicts & Sets Functions & Closures OOP & Classes Data Structures & Algorithms Advanced Python Iterators & Generators Decorators & Context Managers Error Handling & Exceptions Regular Expressions Math & Number Theory Bit Manipulation Dynamic Programming Trees & Binary Trees Graphs & Graph Algorithms Recursion & Backtracking Greedy Algorithms Binary Search Two Pointers & Sliding Window Stacks & Queues Heaps & Priority Queues Linked Lists Matrix & 2D Arrays Datetime & Time Calculations Data Formats & Parsing SQL & SQLite Numpy & Vectorized Computing Cryptography & Hashing

Python Basics easy

Multiplication Table Row

Return the nth row of a multiplication table as a list of 1..n products.

loops lists multiplication

Lists & Arrays easy

Generate a Multiplication Table

Build a function that returns an n x n multiplication table as a list of lists.

nested-loops list-comprehension matrix

Advanced Python easy

Default Argument Trap

Implement a function that safely accumulates items without the classic mutable default argument bug.

default-arguments mutable immutability

Data Formats & Parsing easy

Parse table rows

Implement a function that converts a simple text table into a list of dictionaries.

parsing strings csv

SQL & SQLite easy

Inner Join Two Tables

Write a function that inner joins two lists of dictionaries on a common key and returns the combined rows.

sql join dictionaries

SQL & SQLite easy

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.

sqlite schema table

SQL & SQLite easy

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.

sql sqlite query

SQL & SQLite easy

Customers Never Order

Given Customers and Orders tables, return the names of customers with no orders, sorted alphabetically, or None if all have ordered.

sql sqlite join

SQL & SQLite easy

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.

sqlite alter-table ddl

Showing 1–9 of 9 challenges · easy

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.