- Executors
-
Learn
Learn Python Runnable examples, NumPy, pandas, and more Learn AINeural networks, ML and LLMs from scratch Learn C & C++ Pointers, memory, STL, and modern C++ Learn C#C# basics, OOP, LINQ, async, and .NET exercises Learn MatplotlibLine, bar, scatter and pie charts with live visualizers Python Algorithms Search, sorting, recursion, and visualizers O(n) C & C++ Algorithms Compare algorithms implemented in C and C++ Coding for Kids Learn to code by playing!
- ChallengesNew
- For TeachersNew
- Updates
- Buy me a coffee
JavaScript coding challenges
225 challenges you can solve in JavaScript, from first loops to graphs, dynamic programming and machine learning. Write your code in the browser, run the tests instantly and get an AI review.
Easy · 134 Medium · 67 Hard · 24
Skills you'll practise: CountingDigit extractionString splitting2D listsArithmeticFormulasListsLoopsConditionsDivisibilityFloating pointGradient descent
- Python · C++ · C#
- Automated tests
- AI code review
- Community solutions
- 226
- Challenges
- 123
- Solutions shared
- 9
- Languages
All challenges
Search by topic, language, or difficulty.
Easy
Fibonacci Number
Return the n-th Fibonacci number.
You'll learn
IterationUpdating two variables
Easy
Rectangle Perimeter
Compute the perimeter of a rectangle from its sides.
You'll learn
ArithmeticReturn values
Hard
Minimum Network Connection Cost
Choose undirected links so that every vertex can reach every other vertex, with minimum total cost.
You'll learn
Kruskal's algorithmUnion-find
No solutions yet
Medium
Island Perimeter
Measure the coastline of land cells in a grid.
You'll learn
Edge counting4-neighbor checks
No solutions yet
Medium
Shortest Weighted Routes
Find the minimum total route cost from city 1 to each city.
You'll learn
Dijkstra's algorithmLazy deletion
No solutions yet
Medium
Tic-Tac-Toe Winner
Decide the result of a tic-tac-toe board.
You'll learn
Win conditionsDiagonals
Hard
Trapping Rain Water
Compute how much rain water an elevation map holds.
You'll learn
Two pointersPrefix maxima
Easy
Hollow Square
Draw the outline of a square with * characters.
You'll learn
Edge detectionBuilding strings
Hard
Mini Stack-Language Interpreter
Evaluate a small stack language.
You'll learn
TokenizingExecuting instructions
No solutions yet
Medium
Recursive Palindrome
Check a palindrome recursively, ignoring case and punctuation.
You'll learn
Base casesString cleaning
Hard
Count Inversions
Count the out-of-order pairs in a list.
You'll learn
Merge sortDivide and conquer
No solutions yet
Easy
Min and Max Together
Find the smallest and largest value in one pass.
You'll learn
Single passMultiple return values
Hard
Sliding Window Maximum
Report the maximum of every window of k numbers.
You'll learn
Monotonic dequeO(n) windows
No solutions yet
Easy
Cash: Fewest Coins
Give change with as few U.S. coins as possible.
You'll learn
Greedy algorithmsCoin change
Easy
Halve Until One
Count how many halvings bring a number down to 1.
You'll learn
While loopsCounting
Medium
A* Search on a Weighted Grid
Find the cheapest path across a grid of terrain costs with A*, the search algorithm behind game and robot pathfinding.
You'll learn
A* searchHeuristics
Browse by topic
- Beginner 95
- Ai 47
- Machine Learning 42
- Strings 36
- Arrays 31
- Math 21
- Simulation 19
- Neural Networks 17
- Numbers 16
- Advanced 15
- Dynamic Programming 12
- Parsing 12
- Competitive Programming 10
- Conditions 9
- Design Patterns 8
- Graphs 8
- Grids 8
- Loops 8
- Recursion 7
- Combinatorics 6
- Number Theory 6
- Sorting 6
- Functions 5
- Greedy 5
- Nested Loops 5
- Sequences 5
- Stacks 5
- Variables 5
- Algorithms 4
- Data Structures 4
- Geometry 4
- Patterns 4
- Dictionaries 3
- Fractions 3
- Reinforcement Learning 3
- Sliding Window 3
- Trees 3