Graph DFS
Return all nodes reachable from a start node via DFS.
Topological sort (Kahn)
Return a valid topological ordering of tasks, or [] if a cycle exists.
Word ladder length
Return the length of the shortest transformation from beginWord to endWord changing one letter at a time.
Employee Hierarchy
Build an employee hierarchy tree and compute the total number of direct and indirect reports for each employee.
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.
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.
Eulerian Path Check
Given the number of vertices and an edge list of an undirected graph, decide if it has an Eulerian path.
Employees earning more than manager
Given employee records with manager IDs, find those who earn more than their direct manager.
Accounts Merge
Given a list of accounts, merge those that share any email and return sorted accounts.
Showing 1–9 of 9 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.