- 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 Python Algorithms Search, sorting, recursion, and visualizers O(n) C & C++ Algorithms Compare algorithms implemented in C and C++
- ChallengesNew
C# coding challenges
226 challenges you can solve in C#, 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 · 68 Hard · 24
Skills you'll practise: CountingDigit extractionString splitting2D listsArithmeticFormulasListsLoopsConditionsDivisibilityFloating pointGradient descent
- Python · C++ · C#
- Automated tests
- AI code review
- Community solutions
- 226
- Challenges
- 2
- Solutions shared
- 3
- Languages
All challenges
Search by topic, language, or difficulty.
Medium
Nearest Smaller Value to the Left
For each number, find the closest earlier position containing a strictly smaller number.
You'll learn
Monotonic stackLinear time
No solutions yet
Easy
Palindrome String
Check whether text reads the same forwards and backwards.
You'll learn
Two pointersEarly exit
No solutions yet
Medium
Right-Triangle Product
Find the largest side product of an integer right triangle with a given perimeter.
You'll learn
Right trianglesSearch pruning
No solutions yet
Easy
Acronym Generator
Create an acronym from the first letter of every word, in uppercase.
You'll learn
String parsingWord splitting
No solutions yet
Medium
Number Spiral Lookup
Find a value by row and column in an expanding number spiral.
You'll learn
Math patternsCase analysis
No solutions yet
Easy
Multiplication Table Row
List the first multiples of a number.
You'll learn
MultiplesBuilding lists
No solutions yet
Easy
Title Case
Capitalize the first letter of every word.
You'll learn
String methodsCapitalization
No solutions yet
Easy
Absolute Value Without abs
Compute an absolute value with a condition.
You'll learn
NegationNo built-ins
No solutions yet
Easy
Word Tile Score
Add the tile values for every letter in a word.
You'll learn
Letter scoresSumming with a map
No solutions yet
Easy
Sum of Multiples
Add values below a limit divisible by any supplied factor.
You'll learn
LoopsDivisibility
No solutions yet
Medium
Largest Adjacent-Digit Product
Take every contiguous window of span digits and multiply its digits.
You'll learn
Fixed-size windowsDigit strings
No solutions yet
Easy
Countdown to Liftoff
Count down from a number and end with Liftoff!
You'll learn
Reverse loopsLists
No solutions yet
Medium
Flatten Arbitrarily Nested Lists (Recursion)
Practice recursion by flattening arbitrarily nested lists while skipping null entries.
You'll learn
Base casesNested data
No solutions yet
Easy
Leap Year
Check whether a year follows the Gregorian leap-year rule.
You'll learn
Boolean logicConditions
No solutions yet
Easy
Ticket Price by Age
Choose a cinema ticket price from the visitor's age.
You'll learn
Age rangesBoundary values
No solutions yet
Easy
Pangram Check
A pangram contains every English letter at least once.
You'll learn
Letter setsCase normalization
No solutions yet
Easy
Swap First and Last
Exchange the first and last items of a list.
You'll learn
List indexingSwapping
No solutions yet
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