Sliding window maximum
Return the maximum of each window of size k as it slides across an array.
Median of Two Sorted Arrays
Given two sorted arrays, return the median of the combined sorted array in O(log(min(n,m))) time.
Count of Range Sum
Count contiguous subarrays whose sum lies in a given inclusive range using an efficient divide-and-conquer algorithm.
Largest Rectangle in Histogram
Given an array of bar heights, compute the largest rectangle that can be formed by consecutive bars.
Create Maximum Number
Given two arrays of digits and an integer k, merge them to form the largest number of length k.
Split Array Largest Sum
Minimize the largest sum among k contiguous subarrays using dynamic programming.
Partition to k subsets
Determine if an array of positive integers can be partitioned into k subsets of equal sum using backtracking.
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.
Median of Sorted Array BS
Implement a binary search algorithm to find the median of two sorted arrays efficiently.
Kth Smallest in Sorted Matrix
Implement kth_smallest(matrix, k) to return the kth smallest element in a row- and column-sorted square matrix.
Trapping Rain Water
Given an array of non-negative integers representing an elevation map, compute how much water it can trap after raining.
Subarrays with K different ints
Count the number of contiguous subarrays that contain exactly K distinct integers.
Index of maximum value
Return index of largest value (first on tie).
Add scalar to vector
Add constant k to every element of the vector.
Inclusive numeric range vector
Return [start, start+step, ...] through end inclusive.
Count elements in matrix
Return total scalar count.
Binarize vector at threshold
Return 1.0 where v[i] >= t else 0.0.
Showing 1–17 of 17 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.