Median of Two Sorted Arrays
Given two sorted arrays, return the median of the combined sorted array in O(log(min(n,m))) time.
Palindrome Partitioning Minimum Cuts
Given a string, return the minimum number of cuts needed such that every substring in the partition is a palindrome.
Egg Drop Puzzle
Given k eggs and n floors, compute the minimum number of attempts required in the worst case to find the highest safe floor.
Create Maximum Number
Given two arrays of digits and an integer k, merge them to form the largest number of length k.
Cherry Pickup Maximum
Given a grid with cherries, find the maximum cherries you can collect using two paths from top-left to bottom-right.
Split Array Largest Sum
Minimize the largest sum among k contiguous subarrays using dynamic programming.
Minimum Cut
Given an undirected graph in adjacency-list form, return the size of the minimum edge cut that disconnects the graph.
Swim in Rising Water
Find the minimum time needed to swim from the top-left to the bottom-right of a grid where water level rises and you can only move to cells with elevation ≤ current time.
Partition to k subsets
Determine if an array of positive integers can be partitioned into k subsets of equal sum using backtracking.
Remove invalid parentheses
Given a string with parentheses and letters, return all valid strings after removing the minimum number of invalid parentheses.
Patching Array
Given a sorted array of positive integers and a target n, find the minimum number of patches to make every number from 1 to n representable as a subset sum.
Minimum Window Substring
Implement a sliding window algorithm to find the minimum window substring containing all characters of a given pattern.
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.
Showing 1–13 of 13 challenges · hard
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.