Is pangram
Write a function that determines whether a given string is a pangram, ignoring case and non-letter characters.
Find substring index
Implement a function that returns the starting index of the first occurrence of a substring using only basic string indexing and slicing.
Counting Sort
Implement the counting sort algorithm to sort a list of non-negative integers in O(n + k) time.
Sort List Merge Sort
Write a function that sorts a list of integers using the merge sort algorithm.
Insertion Sort
Implement insertion sort that sorts a list in-place and returns the same list.
Bubble Sort
Implement bubble sort that sorts a list of numbers in ascending order.
Selection Sort Implementation
Implement selection sort to sort a list of numbers in ascending order.
Merge Sort
Implement merge_sort(numbers) that returns a sorted copy of the input list using the merge sort algorithm.
Heap Sort Implementation
Implement the heap sort algorithm to sort a list of comparable elements in non-decreasing order.
Bucket Sort
Implement bucket sort to sort a list of floating-point numbers in the range [0,1).
Shell Sort
Implement Shell sort, an in-place comparison sort that generalizes insertion sort, using a gap sequence that shrinks by half each pass.
Exponential Search
Implement exponential search to find any valid index of a target in a sorted list.
Count of Range Sum
Count contiguous subarrays whose sum lies in a given inclusive range using an efficient divide-and-conquer algorithm.
Jump Search
Implement the jump search algorithm to locate a target in a sorted list, returning its index or -1.
Flood Fill Algorithm
Implement flood fill on a 2D grid using BFS/DFS.
Zeller Congruence Weekday
Implement a function that returns the weekday name for a given date using Zeller's congruence.
Extended Euclidean Algorithm
Implement the extended Euclidean algorithm to return (gcd, x, y) such that ax + by = gcd(a, b).
Isolate Rightmost Set Bit
Given an integer, return a number with only its rightmost set bit set.
Brian Kernighan count
Implement a function that counts set bits using Brian Kernighan's efficient algorithm.
Maximum XOR Pair
Implement max_xor_pair(nums) that returns the maximum XOR value obtainable by pairing any two numbers in the given list.
Levenshtein Distance
Implement the classic Levenshtein distance algorithm to measure string similarity.
Edit Distance (Levenshtein Distance)
Implement the classic edit distance algorithm to find the minimum number of single-character edits required to transform one string into another.
Coin Change Minimum
Given coin denominations and a target amount, compute the minimum number of coins needed or -1 if impossible.
Dijkstra Shortest Path
Implement Dijkstra's algorithm on a weighted graph to return distances from a source to every node.
Showing 1–24 of 36 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.