Find in Mountain Array
Implement a function to search for a target value in a mountain array using binary search.
Maximum Running Time of n Computers
Use binary search to maximize the running time for n computers with batteries.
Magnetic Force Packages
Given basket positions and k balls, find the largest possible minimum distance between any two balls.
Binary Search on Answer: Find the Minimal Maximum Subarray Sum
Implement a function that finds the minimal possible maximum subarray sum when splitting an array into at most k contiguous subarrays.
Lower Bound Binary Search
Implement binary search to find the first index where an element is not less than a given target.
Upper Bound Binary Search
Write a function that returns the index of the first element greater than a target in a sorted list.
Rotated Array Search II
Implement a function to search for a target in a rotated sorted array with possible duplicates.
Kth Smallest in Sorted Matrix
Implement kth_smallest(matrix, k) to return the kth smallest element in a row- and column-sorted square matrix.
First Bad Version
Implement a function to find the first bad version in a sorted range using binary search.
Book Allocation: Minimize Maximum Pages
Implement a function that returns the minimized maximum pages when allocating a list of books to k students.
Minimum Days to Make Bouquets
Given bloomDay per flower, find the minimum day to make m bouquets each needing k adjacent flowers.
Minimum Limit of Balls in a Bag
Given an array of bag sizes and a number of allowed splits, find the minimum possible maximum bag size.
Container With Most Water
Given an array of heights, find the maximum area between two vertical lines that can hold water.
Trapping Rain Water
Given an array of non-negative integers representing an elevation map, compute how much water it can trap after raining.
Best Time to Buy and Sell Stock
Given a list of daily stock prices, determine the maximum profit achievable by buying on one day and selling on a later day.
Sort Colors (Dutch National Flag)
Implement the Dutch National Flag algorithm to sort an array of 0, 1, 2 in one pass.
Count Nice Subarrays
Given an array of integers, count the number of contiguous subarrays that contain exactly k odd numbers.
Subarrays with K different ints
Count the number of contiguous subarrays that contain exactly K distinct integers.
Reduce array to zero
Given an array of non-negative integers, each operation chooses two indices and subtracts 1 from each if both are positive. Return the minimum number of operations to reduce the array to all zeros, or -1 if impossible.
Reverse Pairs Count
Implement a function to count reverse pairs in an array efficiently.
Two Sum Sorted
Given a 1-indexed sorted array and a target, return the two indices that add up to the target.
Three Sum
Given an array of integers, return all unique triplets that sum to zero.
Closest Three Sum
Given an array of integers and a target, return the sum of three numbers that is closest to the target.
Squares of Sorted Array
Implement a function that returns a sorted list of squares for a given non-decreasing integer array.
Showing 97–120 of 170 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.