Advent of Code puzzles in idiomatic Kotlin
Advent of Code is an annual December event, where holiday-themed puzzles are published every day from December 1 to December 25. With the permission of Eric Wastl, creator of Advent of Code, we'll show how to solve these puzzles using the idiomatic Kotlin style:
Advent of Code 2021
Get ready
We'll take you through the basic tips on how to get up and running with solving Advent of Code challenges with Kotlin:
Read our blog post about Advent of Code 2021
Use this GitHub template to create projects
Check out the welcome video by Kotlin Developer Advocate, Sebastian Aigner:
Day 1: Sonar sweep
Apply windowed and count functions to work with pairs and triplets of integers.
Read the puzzle description on Advent of Code
Check out the solution from Anton Arhipov on the Kotlin Blog or watch the video:
Day 2: Dive!
Learn about destructuring declarations and the when expression.
Read the puzzle description on Advent of Code
Check out the solution from Pasha Finkelshteyn on GitHub or watch the video:
Day 3: Binary diagnostic
Explore different ways to work with binary numbers.
Read the puzzle description on Advent of Code
Check out the solution from Sebastian Aigner on Kotlin Blog or watch the video:
Day 4: Giant squid
Learn how to parse the input and introduce some domain classes for more convenient processing.
Read the puzzle description on Advent of Code
Check out the solution from Anton Arhipov on the GitHub or watch the video:
Advent of Code 2020
- Day 1: Report repair
- Day 2: Password philosophy
- Day 3: Toboggan trajectory
- Day 4: Passport processing
- Day 5: Binary boarding
- Day 6: Custom customs
- Day 7: Handy haversacks
- Day 8: Handheld halting
- Day 9: Encoding error
Day 1: Report repair
Explore input handling, iterating over a list, different ways of building a map, and using the let function to simplify your code.
Read the puzzle description on Advent of Code
Check out the solution from Svetlana Isakova on the Kotlin Blog or watch the video:
Day 2: Password philosophy
Explore string utility functions, regular expressions, operations on collections, and how the let function can be helpful to transform your expressions.
Read the puzzle description on Advent of Code
Check out the solution from Svetlana Isakova on the Kotlin Blog or watch the video:
Day 3: Toboggan trajectory
Compare imperative and more functional code styles, work with pairs and the reduce() function, edit code in the column selection mode, and fix integer overflows.
Read the puzzle description on Advent of Code
Check out the solution from Mikhail Dvorkin on GitHub or watch the video:
Day 4: Passport processing
Apply the when expression and explore different ways of how to validate the input: utility functions, working with ranges, checking set membership, and matching a particular regular expression.
Read the puzzle description on Advent of Code
Check out the solution from Sebastian Aigner on the Kotlin Blog or watch the video:
Day 5: Binary boarding
Use the Kotlin standard library functions (replace(), toInt(), find()) to work with the binary representation of numbers, explore powerful local functions, and learn how to use the max() function in Kotlin 1.5.
Read the puzzle description on Advent of Code
Check out the solution from Svetlana Isakova on the Kotlin Blog or watch the video:
Day 6: Custom customs
Learn how to group and count characters in strings and collections using the standard library functions: map(), reduce(), sumOf(), intersect(), and union().
Read the puzzle description on Advent of Code
Check out the solution from Anton Arhipov on the Kotlin Blog or watch the video:
Day 7: Handy haversacks
Learn how to use regular expressions, use Java's compute() method for HashMaps from Kotlin for dynamic calculations of the value in the map, use the forEachLine() function to read files, and compare two types of search algorithms: depth-first and breadth-first.
Read the puzzle description on Advent of Code
Check out the solution from Pasha Finkelshteyn on the Kotlin Blog or watch the video:
Day 8: Handheld halting
Apply sealed classes and lambdas to represent instructions, apply Kotlin sets to discover loops in the program execution, use sequences and the sequence { } builder function to construct a lazy collection, and try the experimental measureTimedValue() function to check performance metrics.
Read the puzzle description on Advent of Code
Check out the solution from Sebastian Aigner on the Kotlin Blog or watch the video:
Day 9: Encoding error
Explore different ways to manipulate lists in Kotlin using the any(), firstOrNull(), firstNotNullOfOrNull(), windowed(), takeIf(), and scan() functions, which exemplify an idiomatic Kotlin style.
Read the puzzle description on Advent of Code
Check out the solution from Svetlana Isakova on the Kotlin Blog or watch the video:
What's next?
Complete more tasks with Kotlin Koans
Create working applications with the free Kotlin Core track by JetBrains Academy