Practice Arena

Python Coding
Challenges

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819 challenges 506 easy 280 medium 33 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

Limit and Offset Query

Write a function that returns a page from a dataset given limit and offset.

pagination list slicing

Data Structures & Algorithms medium

Online Stock Span

Implement StockSpanner.next(price) that returns the maximum number of consecutive days (including today) with price <= current price.

stack monotonic-stack stock-span

SQL & SQLite medium

Index Creation Query

Create an in-memory SQLite database, execute CREATE INDEX statements, and return the resulting index metadata rows.

sqlite create-index schema

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 medium

Nth Highest Salary

Write a Python function using SQLite to return the Nth highest distinct salary from an employee table.

sql sqlite aggregation

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

Cumulative Sum SQL

Write a SQL query to compute cumulative sales totals per product ordered by sale date.

sql window-functions running-total

Showing 7 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.