Practice Arena

Python Coding
Challenges

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925 challenges 556 easy 323 medium 46 hard

All Easy Medium Hard

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

Numpy & Vectorized Computing hard

Inclusive numeric range vector

Return [start, start+step, ...] through end inclusive.

vectors arrays numpy-style

Numpy & Vectorized Computing hard

Count elements in matrix

Return total scalar count.

vectors arrays numpy-style

Numpy & Vectorized Computing hard

Binarize vector at threshold

Return 1.0 where v[i] >= t else 0.0.

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

Constant Time Compare

Write a function that compares two strings without leaking length or content via timing.

constant-time security comparison

Cryptography & Hashing easy

Verify HMAC signature

Implement a function that verifies an HMAC-SHA256 signature for a message and key.

hmac hashlib security

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

XOR Cipher Encode

Implement the XOR cipher: encode a string by XORing each character with a key character.

xor encryption strings

Cryptography & Hashing easy

Constant time compare

Write a function that compares two strings in constant time to avoid timing attacks.

timing-safe security strings

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

Cryptography & Hashing easy

Verify HMAC signature

Implement a function that verifies an HMAC-SHA256 signature for a given message and secret key.

hmac sha256 security

Showing 913–925 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.