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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

BFS level-order traversal

Return the level-order traversal of a binary tree as a list of lists.

BFS trees queues

Data Structures & Algorithms medium

Graph DFS

Return all nodes reachable from a start node via DFS.

graph DFS recursion

Data Structures & Algorithms medium

Find Peak Element

Implement a function that returns the index of any peak element in an integer array.

arrays search binary-search

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

Path Sum II All Paths

Return all root-to-leaf paths where the sum of node values equals a target.

binary-tree dfs backtracking

Data Structures & Algorithms medium

Redundant Connection

Given a list of edges forming a tree plus one extra edge, return the edge that appears last in the input and creates a cycle.

graphs union-find cycle-detection

Showing 7 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.