Practice Arena

Python Coding
Challenges

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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

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

Select All Users

Write a function that connects to an in-memory SQLite database and returns all users as a list of lists.

sqlite sql query

Numpy & Vectorized Computing easy

Dot product of two vectors

Return sum of element-wise products.

vectors arrays numpy-style

Numpy & Vectorized Computing easy

Mean of a vector

Return arithmetic mean or 0.0 when empty.

vectors arrays numpy-style

Numpy & Vectorized Computing easy

Maximum element in vector

Return largest value or None when empty.

vectors arrays numpy-style

Numpy & Vectorized Computing easy

Minimum element in vector

Return smallest value or None when empty.

vectors arrays numpy-style

Numpy & Vectorized Computing easy

Sum each matrix row

Given rows, return each row sum.

vectors arrays numpy-style

Numpy & Vectorized Computing easy

Sum each matrix column

Return column totals for a rectangular matrix.

vectors arrays numpy-style

Cryptography & Hashing easy

SHA256 Hash String

Write a function that returns the SHA256 hexadecimal digest of a given string.

hashing sha256 hashlib

Cryptography & Hashing easy

Compute SHA-1 Hash String

Write a function that returns the SHA-1 hash of a string as a 40-character hex string.

sha1 hashlib hashing

Cryptography & Hashing easy

Password Salt Hash

Implement a function that returns a secure salted SHA-256 password hash with a deterministic format.

hashlib sha256 security

Cryptography & Hashing easy

SHA1 Hash String

Implement a function that returns the SHA1 hexadecimal digest of an input string.

sha1 hashlib hashing

Cryptography & Hashing easy

Compute SHA256 Hash String

Implement a function that returns the SHA-256 hex digest of a given input string.

sha256 hashing hashlib

Showing 241–255 of 255 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.