N-Queens Solutions
Implement a function to count the number of distinct ways to place n queens on an n×n board.
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).
Partition to k subsets
Determine if an array of positive integers can be partitioned into k subsets of equal sum using backtracking.
Remove invalid parentheses
Given a string with parentheses and letters, return all valid strings after removing the minimum number of invalid parentheses.
Hamiltonian Cycle Backtrack
Implement a backtracking algorithm to find a Hamiltonian cycle in an undirected graph.
Showing 1–5 of 5 challenges · hard
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.