Maximum subarray (Kadane)
Find the contiguous subarray with the largest sum.
Rotate array
Rotate a list right by k positions in place.
Remove duplicates (sorted)
Return a sorted list with duplicates removed.
Merge two sorted arrays
Merge two sorted arrays into one sorted array.
Product except self
Return an array where output[i] is the product of all elements except nums[i], without using division.
Sliding window maximum
Return the maximum of each window of size k as it slides across an array.
Subarray sum equals K
Count the number of contiguous subarrays whose sum equals k.
Showing 7 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.