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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
- Python · C++ · C#
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All challenges
Search by topic, language, or difficulty.
Easy
Above-Average Values
Keep the values that are greater than the average.
You'll learn
Two passesFiltering
No solutions yet
Easy
Fizz Buzz
Build a sequence using divisibility by 3 and 5.
You'll learn
ConditionsDivisibility
No solutions yet
Easy
Second Largest Value
Find the second largest distinct value.
You'll learn
Two trackersDistinct values
No solutions yet
Easy
Array Maximum
Find the largest value in a list.
You'll learn
Tracking a maximumSingle pass
No solutions yet
Easy
Array Minimum
Find the smallest value in a list.
You'll learn
Tracking a minimumSingle pass
No solutions yet
Medium
Forward Propagation in a Two-Layer Network
Run inputs through a hidden ReLU layer and a sigmoid output layer.
You'll learn
Forward passMulti-layer networks
No solutions yet
Medium
Q-Learning Updates
Apply the Q-learning update to a stream of experiences and watch rewards flow back to earlier states.
You'll learn
Q-learningDiscounted rewards
No solutions yet
Easy
Longest Word
Find the longest word in a sentence.
You'll learn
String splittingTracking a maximum
No solutions yet
Easy
Epsilon-Greedy Multi-Armed Bandit
Balance exploration and exploitation on a multi-armed bandit with epsilon-greedy action selection.
You'll learn
Explore vs exploitBandits
No solutions yet
Medium
Perceptron Learning Algorithm
Train the original perceptron, which updates its weights only when it makes a mistake.
You'll learn
PerceptronOnline learning
No solutions yet
Easy
Classify a Number by Its Divisors
Classify a positive integer as perfect, abundant, or deficient.
You'll learn
DivisorsClassification
No solutions yet
Easy
Pascal’s Triangle
Build rows by adding neighboring entries from the previous row.
You'll learn
2D listsBuilding from previous rows
No solutions yet
Easy
Count Words
Count the words in a sentence.
You'll learn
String splittingWhitespace
No solutions yet
Easy
Running Sum
Replace each value with the total so far.
You'll learn
Prefix sumsLists
No solutions yet
Easy
Array Average
Compute the average of a list of numbers.
You'll learn
Sum and countFloat division
No solutions yet
Easy
Move Zeroes
Move every zero to the end while keeping the other order.
You'll learn
Two pointersIn-place updates
No solutions yet
Easy
Activation Functions
Apply sigmoid, ReLU, Leaky ReLU or tanh to every value in a list.
You'll learn
SigmoidReLU and tanh
No solutions yet
Easy
Rotate Array
Rotate a list to the right by some steps.
You'll learn
Array indexingModulo
No solutions yet
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