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.
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.
Combination Generator
Write a recursive function that returns all combinations of length k from a list of distinct integers.
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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.