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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

Data Structures & Algorithms medium

Count inversions lite

Implement a function that counts inversions in a list of numbers efficiently.

inversions sorting merge sort

Data Structures & Algorithms easy

Count pairs with given difference

Count how many unordered pairs in a list have a given absolute difference using an efficient approach.

hash map counting arrays

Data Structures & Algorithms medium

Radix Sort

Implement LSD radix sort to sort a list of non-negative integers in ascending order.

radix-sort sorting counting-sort

Data Structures & Algorithms medium

Decode Ways

Count the number of ways to decode a numeric string into letters using the mapping A=1 to Z=26.

dynamic programming strings counting

Showing 4 challenges · Data Structures & Algorithms

Data Structures & Algorithms — Python coding challenges

What you will find here

This page lists data structures & algorithms challenges — real Python problems you solve in the browser IDE with instant test feedback. Each challenge includes a clear brief, starter code, and automated checks.

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.