Union Find Class
Implement a UnionFind class with find and union operations supporting path compression and union by size.
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.
Accounts Merge
Given a list of accounts, merge those that share any email and return sorted accounts.
Kruskal MST
Implement Kruskal's algorithm to compute the total weight of a minimum spanning tree in a connected undirected graph.
Most stones removed
Given stone coordinates on a grid, find the maximum number of stones that can be removed while every stone shares a row or column with another remaining stone.
Regions Cut by Slashes
Given a grid of slashes, count the number of connected regions formed by the slashes and the grid borders.
Showing 1–6 of 6 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.