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875 challenges 536 easy 303 medium 36 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

Coin change (DP)

Find the minimum number of coins to make exactly the target amount.

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 medium

Merge Sort

Implement merge_sort(numbers) that returns a sorted copy of the input list using the merge sort algorithm.

sorting recursion divide-and-conquer

Data Structures & Algorithms medium

Bucket Sort

Implement bucket sort to sort a list of floating-point numbers in the range [0,1).

sorting bucket-sort insertion-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

Data Structures & Algorithms medium

Online Stock Span

Implement StockSpanner.next(price) that returns the maximum number of consecutive days (including today) with price <= current price.

stack monotonic-stack stock-span

Data Structures & Algorithms medium

Eulerian Path Check

Given the number of vertices and an edge list of an undirected graph, decide if it has an Eulerian path.

graph eulerian degree

Data Structures & Algorithms medium

Strobogrammatic number II

Given a positive integer n, return all strobogrammatic numbers of length n in ascending order.

strings recursion number

Showing 8 challenges · medium · 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.