Graph DFS
Return all nodes reachable from a start node via DFS.
Employee Hierarchy
Build an employee hierarchy tree and compute the total number of direct and indirect reports for each employee.
Path Sum II All Paths
Return all root-to-leaf paths where the sum of node values equals a target.
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.
Flood Fill Algorithm
Implement flood fill on a 2D grid using BFS/DFS.
Matchsticks to Square
Given a list of matchstick lengths, decide if they can form a square by using each matchstick exactly once.
Knight Tour Count
Implement a backtracking search to count all ways a knight can visit every cell on a 5x5 board exactly once starting from (0,0).
Showing 1–7 of 7 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.