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Kotlin coding challenges
225 challenges you can solve in Kotlin, 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
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All challenges
Search by topic, language, or difficulty.
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
Greatest Common Divisor
Find the largest number that divides both values.
You'll learn
Euclid's algorithmModulo
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
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
Medium
Empty Two Coin Piles
Decide whether paired removals can empty two piles.
You'll learn
Math reasoningInvariants
No solutions yet
Medium
One Generation of a Genetic Algorithm
Breed the next generation of bit strings with tournament selection, single-point crossover and mutation.
You'll learn
Genetic algorithmsEvolutionary search
No solutions yet
Easy
Power by Repeated Multiplication
Raise a number to a power with a loop.
You'll learn
Running productZero exponent
Medium
Exact Fraction Arithmetic
Perform fraction operations and return a reduced fraction.
You'll learn
GCD reductionSign normalization
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
Count Dice Sequences
Count ordered die-roll sequences with a given total.
You'll learn
RecurrencesModular counting
No solutions yet
Easy
Countdown to Liftoff
Count down from a number and end with Liftoff!
You'll learn
Reverse loopsLists
Easy
Triangle Classification
Classify three side lengths as invalid, equilateral, isosceles, or scalene.
You'll learn
Triangle inequalityOrdering conditions
No solutions yet
Easy
Multiplication Table Row
List the first multiples of a number.
You'll learn
MultiplesBuilding lists
Medium
Can We Split Into Two Teams?
Decide whether people can be assigned to two teams so that each listed pair is on opposite teams.
You'll learn
Graph coloringBFS
No solutions yet
Easy
Largest of Three
Pick the largest of three numbers without a built-in max.
You'll learn
ComparisonsCombining conditions
Medium
Minesweeper Neighbor Counts
Annotate a rectangular board.
You'll learn
8-neighbor checksBoundary handling
No solutions yet
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