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

Python Basics easy

Sum of digits

Return the sum of all decimal digits of a non-negative integer.

arithmetic loops

Python Basics easy

Digit count of an integer

Given an integer, return the number of digits it has, handling negatives and zero correctly.

integers loops arithmetic

Python Basics easy

Digit Count

Count the number of digits in an integer using arithmetic, without string conversion.

numbers loops math

Strings & Text easy

Extract Digits Only

Given a string that may contain letters, symbols, and whitespace, extract all digits in order and return them as an integer.

strings digits parsing

Strings & Text easy

Extract digits from string

Write a function that extracts all digit characters from a given string, preserving their original order.

strings digits parsing

Iterators & Generators easy

Digit Expansion Generator

Create a generator that lazily yields each decimal digit of a non-negative integer from most significant to least significant.

generators yield digits

Math & Number Theory easy

Harshad Number Check

Write a function that checks if a number is a Harshad (or Niven) number.

math digits divisibility

Dynamic Programming hard

Create Maximum Number

Given two arrays of digits and an integer k, merge them to form the largest number of length k.

arrays greedy dynamic-programming

Recursion & Backtracking medium

Letter Combinations of a Phone Number

Given a string of digits, return all possible letter combinations that the number could represent on a phone keypad.

recursion backtracking string

Greedy Algorithms hard

Remove K Digits to Form the Smallest Number

Given a non-negative integer as a string, remove exactly k digits to form the smallest possible integer without leading zeros.

greedy stack string

Stacks & Queues medium

Remove K Digits Stack

Remove k digits from a non-negative integer string to produce the smallest possible number using a stack-based approach.

stack string greedy

Showing 1–11 of 11 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.