Delete Node in BST
Implement a function that deletes a key from a binary search tree and returns the new root.
Validate BST
Implement a function to determine if a binary tree is a valid Binary Search Tree.
Kth Smallest in BST
Implement a function that returns the k-th smallest value in a binary search tree.
Search in Rotated Array
Implement an efficient search in a rotated sorted array using modified binary search.
Kth Missing Positive
Given a strictly increasing array and an integer k, return the k-th positive integer that is missing from the array.
Find in Mountain Array
Implement a function to search for a target value in a mountain array using binary search.
Maximum Running Time of n Computers
Use binary search to maximize the running time for n computers with batteries.
Binary Search on Answer: Find the Minimal Maximum Subarray Sum
Implement a function that finds the minimal possible maximum subarray sum when splitting an array into at most k contiguous subarrays.
Search 2D Matrix
Given a sorted 2D matrix with sorted rows and first element of each row greater than last of previous, find target efficiently.
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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.