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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#
  • Automated tests
  • AI code review
  • Community solutions
Programming
Programming fundamentalsFrom variables to recursion, for beginners
AI and machine learning
AI Learning HubNeural networks, ML and LLMs from scratch Neural networks from scratchNeurons, backpropagation and optimizers Machine learning from scratchRegression, classification and clustering Transformers and LLMs from scratchTokenizers, attention and text generation Classical AI and reinforcement learningSearch, games and reinforcement learning
226
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All challenges

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226 challenges
Easy

Sum the Valid Numbers

Add up the entries that are whole numbers and skip everything else, the way try/except handles bad input.

You'll learn Try/exceptInput validation
BeginnerParsingStrings
Python C++ C#
0 solved
No solutions yet
Easy

Factorial

Multiply all positive integers up to n.

You'll learn LoopsRunning product
Beginner
Python C++ C#
0 solved
No solutions yet
Easy

Largest Digit

Find the largest decimal digit of a positive integer.

You'll learn Digit extractionTracking a maximum
Beginner
Python C++ C#
0 solved
No solutions yet
Easy

Count Log Levels

Read the lines of a log file and count how many are INFO, WARNING and ERROR.

You'll learn Reading linesString splitting
BeginnerParsingStrings
Python C++ C#
0 solved
No solutions yet
Easy

Sum of Digits

Add up the decimal digits of a positive integer.

You'll learn Modulo and divisionWhile loops
Beginner
Python C++ C#
0 solved
No solutions yet
Easy

Triangular Number

Add the integers from 1 through n.

You'll learn LoopsArithmetic series
Beginner
Python C++ C#
0 solved
No solutions yet
Medium

Parallel Task Completion Order

Run tasks concurrently with at most k at a time and report the order in which they finish.

You'll learn ConcurrencyPriority queues
SimulationSorting
Python C++ C#
0 solved
No solutions yet
Easy

Square a Number

Multiply an integer by itself.

You'll learn FunctionsArithmetic
Beginner
Python C++ C#
0 solved
No solutions yet
Easy

Reverse a Number

Reverse the decimal digits of a positive integer.

You'll learn Digit extractionBuilding numbers
Beginner
Python C++ C#
0 solved
No solutions yet
Easy

One Shared Configuration

Simulate a singleton settings object: every part of the program reads and writes the same instance.

You'll learn SingletonShared state
BeginnerDesign patternsSimulation
Python C++ C#
0 solved
No solutions yet
Easy

Count Digits

Count the decimal digits of a positive integer.

You'll learn Integer divisionCounting loops
Beginner
Python C++ C#
0 solved
No solutions yet
Easy

Checkout Facade

Hide stock checks and price totals behind one simple checkout call.

You'll learn Facade patternValidation
ArraysDesign patternsSimulation
Python C++ C#
0 solved
No solutions yet
Hard

Scaled Dot-Product Attention

Implement the attention operation at the heart of Transformers and large language models.

You'll learn AttentionTransformers
aimachine learning
Python C++ C#
0 solved
No solutions yet
Medium

RAII Release Order

Work out the order in which scoped resources are released when their scopes end, as RAII guarantees.

You'll learn RAIIStacks
Data-structuresSimulationStacks
Python C++ C#
0 solved
No solutions yet
Easy

Notification Costs

Send messages through email, SMS and push channels that each compute their own cost.

You'll learn PolymorphismInteger division
SimulationStrings
Python C++ C#
0 solved
No solutions yet
Easy

Join Customers and Orders

Join customers with their orders like a LINQ Join and report each customer's total spend.

You'll learn LINQ JoinGrouping
ArraysSorting
Python C++ C#
0 solved
No solutions yet
Easy

Bank Account Rules

Protect an account's balance behind deposit and withdraw rules, rejecting invalid operations.

You'll learn EncapsulationBusiness rules
BeginnerSimulation
Python C++ C#
0 solved
No solutions yet
Easy

Unique Records

Remove duplicate records that are equal by value, keeping the first of each in order.

You'll learn RecordsValue equality
BeginnerStrings
Python C++ C#
0 solved
No solutions yet

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