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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
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- 226
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All challenges
Search by topic, language, or difficulty.
Easy
Collatz Sequence
Follow the halve-or-triple-and-add-one rule until reaching 1.
You'll learn
While loopsStep counting
No solutions yet
Medium
Raise a Fraction to a Real Power
Raise a positive fraction to a real-valued exponent.
You'll learn
Real exponentsFloating point
No solutions yet
Easy
Simple Interest
Find the total amount after simple interest.
You'll learn
PercentagesWord problems
No solutions yet
Easy
Character Frequency
Count how often each character appears.
You'll learn
Frequency tablesCounting
No solutions yet
Medium
Raise a Number to a Fractional Power
Raise a positive real number to a rational exponent.
You'll learn
Roots and powersFloating point
No solutions yet
Medium
Factory Production Time
Find the earliest time parallel machines can finish a target number of items.
You'll learn
Binary search on answerMonotonic checks
No solutions yet
Medium
Count Dice Sequences
Count ordered die-roll sequences with a given total.
You'll learn
RecurrencesModular counting
No solutions yet
Medium
Count Coin Combinations
Count ways to make an amount with unlimited coins of specified denominations.
You'll learn
Unbounded knapsackCounting combinations
No solutions yet
Medium
Readability Grade
Estimate the school grade needed to read a text.
You'll learn
Text analysisFormulas
No solutions yet
Easy
First Unique Character
Find the first character that appears only once.
You'll learn
Hash mapsCounting
No solutions yet
Medium
Empty Two Coin Piles
Decide whether paired removals can empty two piles.
You'll learn
Math reasoningInvariants
No solutions yet
Easy
Password Rules Check
Check a password against simple strength rules.
You'll learn
ValidationBoolean flags
No solutions yet
Medium
Robot Command Simulator
Move a robot using L (turn left 90 degrees), R (turn right 90 degrees), and A (advance one step).
You'll learn
Direction vectorsCommand processing
No solutions yet
Medium
Tree Diameter
A tree is a connected undirected graph with no cycles.
You'll learn
Double BFSAdjacency lists
No solutions yet
Easy
Power of Two
Check whether a number is a power of two.
You'll learn
Bit manipulationDivision
No solutions yet
Medium
Exact Fraction Arithmetic
Perform fraction operations and return a reduced fraction.
You'll learn
GCD reductionSign normalization
No solutions yet
Easy
Least Common Multiple
Find the smallest positive number divisible by both values.
You'll learn
GCD and LCMNumber theory
No solutions yet
Easy
Palindrome Number
Check whether a number reads the same backwards.
You'll learn
Digit reversalComparisons
No solutions yet
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