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467 challenges 330 easy 120 medium 17 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

Lists & Arrays medium

Maximum subarray (Kadane)

Find the contiguous subarray with the largest sum.

dp arrays kadane

Lists & Arrays medium

Partition Array

Implement a function that finds a contiguous partition of a list into k groups, minimizing the maximum sum of the groups.

arrays partition contiguous

Dicts & Sets medium

Subarray sum equals K

Count the number of contiguous subarrays whose sum equals k.

prefix-sum dict arrays

Dynamic Programming medium

Kadane Variant: Maximum Product Subarray

Implement max_product_subarray(nums) that returns the maximum product of any contiguous subarray.

kadane subarray product

Two Pointers & Sliding Window medium

Permutation in String

Determine if any permutation of a shorter string appears as a contiguous substring in a longer string using an efficient sliding window.

sliding-window two-pointers hash-map

Two Pointers & Sliding Window medium

Count Nice Subarrays

Given an array of integers, count the number of contiguous subarrays that contain exactly k odd numbers.

sliding-window two-pointers subarray

Showing 6 challenges · medium

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.