Condition Variable Waiter
Implement a deterministic simulation of a waiter whose tray has limited capacity and who becomes busy for a fixed time after each pickup.
Safe Command Executor
Implement emulate_run that simulates running a command list and returns output and exit code.
Crawler Log Folder
Given a list of folder navigation operations, compute the minimum steps required to return to the main folder.
Design Twitter Feed
Implement a Twitter class with postTweet, getNewsFeed, follow, and unfollow methods.
Seat Manager Design
Implement a SeatManager class that supports reserving the smallest available seat and unreserving seats.
Jump Game on Graph
Implement a function that determines if you can reach the last node of a directed graph by jumping from node 0 to node n-1 using edges.
Lemonade Change
Simulate a lemonade stand and decide if you can provide change for each customer using only $5, $10, and $20 bills.
Gas Station Circuit
Given gas and cost arrays for a circular route, determine the starting gas station index that allows a full loop, or -1 if none exists.
Minimum Speed to Arrive on Time
Given commute distances and a time limit, compute the minimum integer speed so you arrive on time.
Trapping Rain Water
Given an array of non-negative integers representing an elevation map, compute how much water it can trap after raining.
Validate Stack Sequences
Given two sequences of distinct integers, verify whether the second sequence is a valid pop order for a stack given the first sequence as push order.
Asteroid Collision
Simulate asteroid collisions with a stack and return the remaining asteroids in original order.
Last Stone Weight
Given an array of stone weights, repeatedly smash the two heaviest stones and return the last remaining weight or 0.
Spiral Matrix Order
Given a 2D matrix, return all elements in clockwise spiral order starting from the top-left.
Rotting Oranges Time
Given a grid of fresh, rotten, and empty cells, compute the minimum minutes until all fresh oranges rot, or -1 if some are unreachable.
Spiral Matrix Traversal
Implement a function that returns the elements of a 2D matrix in clockwise spiral order.
Largest Plus Sign
Compute the largest possible plus sign of 1s in an n x n grid with some cells set to 0.
Showing 1–17 of 17 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.