Max of a variable-length list
Implement a function that returns the maximum value from a list of numbers without using max().
Max of three numbers
Implement a function that returns the maximum of three numbers using comparisons.
Maximum subarray (Kadane)
Find the contiguous subarray with the largest sum.
Sliding window maximum
Return the maximum of each window of size k as it slides across an array.
Running Maximum
Implement a function that returns a list where each element is the largest value seen so far.
Partition Array
Implement a function that finds a contiguous partition of a list into k groups, minimizing the maximum sum of the groups.
Rate Limit Decorator
Implement a decorator that enforces a maximum number of calls per second for any function.
Kadane Variant: Maximum Product Subarray
Implement max_product_subarray(nums) that returns the maximum product of any contiguous subarray.
Max Profit from Selling Twice
Compute the maximum profit that can be achieved by completing at most two buy-sell transactions on a given price array.
House Robber
Given a list of house values, return the maximum sum you can rob without robbing two adjacent houses.
Unbounded Knapsack
Given item weights and values with unlimited copies, find the maximum total value that fits in a knapsack capacity.
Buy Sell Stock with Cooldown (DP)
Given daily stock prices, compute the maximum profit you can achieve if you must wait one day after selling before buying again.
Maximum depth of tree
Implement max_depth(root) to return the maximum depth of a binary tree.
Stock Buy Sell Once
Given daily stock prices, compute the maximum profit you can achieve from buying once and selling once later.
Ternary Search
Implement ternary search to locate the maximum of a discrete unimodal function.
Container With Most Water
Given an array of heights, find the maximum area between two vertical lines that can hold water.
Best Time to Buy and Sell Stock
Given a list of daily stock prices, determine the maximum profit achievable by buying on one day and selling on a later day.
Max Area of Island
Given a 2D grid of 0s and 1s, find the maximum area of a connected group of 1s.
Showing 18 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.