Decode Ways
Count the number of ways to decode a numeric string into letters using the mapping A=1 to Z=26.
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.
Bell number
Implement a function to compute the Bell number B(n) using dynamic programming.
0/1 Knapsack
Implement the classic 0/1 Knapsack dynamic programming solution to maximize value under a weight capacity.
Coin Change Ways
Count the number of distinct combinations of coins that sum to a target amount.
Ugly Number II
Given an integer n, return the nth ugly number using an efficient dynamic programming approach.
Minimum Falling Path Sum
Compute the minimum falling path sum in an n x n matrix by moving down or diagonally each step.
Matrix Chain Multiplication
Given a list of matrix dimensions, compute the minimum multiplication cost using dynamic programming.
Target sum assignments
Given a list of integers and a target, count how many ways to assign + or - to each number so the total equals the target.
Subset Sum Exists
Given a list of positive integers and a target sum, return whether some subset adds up exactly to the target.
Maximal rectangle in matrix
Given a matrix of 0s and 1s, compute the area of the largest rectangle consisting only of 1s.
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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.