Longest Substring with K Repeating Characters
Return the length of the longest substring of a given string in which every character appears at least K times.
Jump Game Minimum Jumps
Given an array of non-negative integers where each element is the maximum jump length, compute the minimum jumps to reach the last index.
Find all anagrams
Return all starting indices where any anagram of a given word appears as a substring.
Substring Anagrams
Return all start indices in a string where a substring of length k is an anagram of a pattern string.
Convolve 1D Signal
Write a function that computes the 1D convolution of two lists in 'full' mode.
Character Replacement Window
Given a string and a number k, find the length of the longest substring that can be made uniform by replacing at most k characters.
Permutation in String
Determine if any permutation of a shorter string appears as a contiguous substring in a longer string using an efficient sliding window.
Count Nice Subarrays
Given an array of integers, count the number of contiguous subarrays that contain exactly k odd numbers.
Minimum Size Subarray Sum
Given an array of positive integers, return the minimal length of a contiguous subarray with sum at least target, or 0 if none exists.
Fruit into Baskets
Given an array of integers representing fruit types, return the maximum number of fruits you can collect in a contiguous subarray with at most two distinct types.
Binary Subarray with Sum
Given a binary list and a goal sum, count the number of subarrays that add up to that goal.
Subarray product less than K
Count contiguous subarrays where the product of all elements is strictly less than a target K.
Longest Substring with At Most K Distinct Characters
Given a string and an integer k, find the length of the longest substring that contains at most k distinct characters.
Sliding Window Median
Given a list of integers and a positive window size k, return the median of each sliding window of length k.
Longest Repeating Character Replacement
Given a string and an integer k, return the length of the longest substring that can be made of identical characters after at most k replacements.
Count Nice Subarrays
Count subarrays that contain exactly k odd numbers.
Sliding Window Maximum using Heap
Given an array of integers and a window size k, return an array of maximums for each contiguous subarray of length k.
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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.