Hamiltonian Path Check
Implement a function that checks whether an undirected graph has a Hamiltonian path using DFS and backtracking.
All Paths from Source to Target
Given a directed acyclic graph, return all paths from node 0 to the last node.
Network Delay Time
Given a directed weighted graph and a starting node, find the minimum time for a signal to reach all nodes, or -1 if unreachable.
Cheapest Flights Within K Stops
Implement a function to compute the cheapest flight price from source to destination with at most K stops in a directed weighted graph.
Floyd-Warshall: All-Pairs Shortest Paths
Implement the Floyd-Warshall algorithm to find all-pairs shortest path distances in a directed graph with possibly negative weights but no negative cycles.
Rat in a Maze
Count the number of distinct paths a rat can take from top-left to bottom-right in a binary grid, moving down or right and avoiding walls.
Shortest Path in Binary Matrix
Compute the shortest path length from top-left to bottom-right in a binary matrix using 8-directional moves.
Showing 25–31 of 31 challenges
Guide: free Python coding challenges
Practice Python by solving problems
PythonSkillset challenges are hands-on coding exercises from beginner to advanced. Open a challenge, read the problem, write Python in the split-pane editor, and run tests with Pyodide — no install required.
How to use the arena
- Pick a category — basics, algorithms, strings, and more
- Open a challenge, read the statement, and edit the starter code
- Run tests, fix failures, then try a related quiz or tutorial lesson
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.