Create Maximum Number
Given two arrays of digits and an integer k, merge them to form the largest number of length k.
Unique Paths in a Grid
Count distinct paths in an m x n grid moving only down or right.
Cherry Pickup Maximum
Given a grid with cherries, find the maximum cherries you can collect using two paths from top-left to bottom-right.
Maximal square matrix
Given a 2D binary matrix of 0s and 1s, find the side length of the largest square containing only 1s.
Derangement count
Implement a function to count derangements of n items using the classic recurrence.
Shortest Common Supersequence
Given two strings, return any shortest supersequence that contains both as subsequences.
Interleaving string
Given three strings s1, s2, and s3, check if s3 is formed by interleaving s1 and s2 while preserving the order of each input string.
Count subsets with sum
Given a list of integers and a target sum, count how many subsets of the list sum to the target.
Matrix Chain Multiplication
Given a list of matrix dimensions, compute the minimum multiplication cost using dynamic programming.
Tiling dominoes count
Given a 2 x n board, count the distinct tilings using 2 x 1 dominoes.
Delete and Earn
Given an array of integers, find the maximum points you can earn by repeatedly deleting a number and all its adjacent values.
Split Array Largest Sum
Minimize the largest sum among k contiguous subarrays using dynamic programming.
Minimum Path Sum Matrix
Implement a function that computes the minimum path sum from the top-left to the bottom-right of a grid moving only right or down.
Dungeon Game Minimum Health
Compute the minimum initial health needed to reach the bottom-right corner of a dungeon grid without health dropping to zero or below.
Floyd-Warshall: All-Pairs Shortest Paths
Implement the Floyd-Warshall algorithm to find all-pairs shortest path distances in a directed graph with possibly negative weights but no negative cycles.
Minimum Window Subsequence
Given strings s and t, return the minimum window substring of s that contains t as a subsequence, or empty string if none exists.
Count square submatrices with all ones
Count all square submatrices consisting entirely of 1s in a binary matrix.
Largest Plus Sign
Compute the largest possible plus sign of 1s in an n x n grid with some cells set to 0.
Showing 25–42 of 42 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.