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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

Quicksort

Implement quicksort and return a sorted list.

sorting recursion divide-and-conquer

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

Longest Consecutive Sequence

Given an unsorted list of integers, find the length of the longest consecutive elements sequence in O(n) time.

hash set array linear

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

Heap Sort Implementation

Implement the heap sort algorithm to sort a list of comparable elements in non-decreasing order.

heap sorting in-place

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

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

Reconstruct Itinerary

Given a list of airline tickets, reconstruct the itinerary in order using each ticket exactly once, choosing the lexicographically smallest path when multiple options exist.

graph backtracking dfs

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.