Starter template for solving Advent of Code in Kotlin


  • Gradle setup so you can run a specific day or all days on the command line (see Running below)
  • Timings for each part of each day
  • Input for each day automatically exposed in String and List form
  • Junit and Hamcrest test libraries included (see Testing below)
  • Starter .gitignore


Project is already setup with gradle. To run the app:

  • Navigate to top-level directory on the command line
  • Run ./gradlew run to run all days
  • Run ./gradlew run --args $DAY where $DAY is an integer to run a specific day


Project includes Junit and Hamcrest and a stub unit test to get you going. To run all tests:

  • Navigate to top-level directory on the command line
  • Run ./gradlew test
  • Add --info, --debug or --stacktrace flags for more output
Test input

By default, instantiations of Day classes in tests will use the input files in src/test/resources, not those in src/main/resources.
This hopefully gives you flexibility – you could either just copy the real input into src/test/resources if you want to test
the actual answers, or you could add a file of test data based on the examples given on the Advent of Code description for the day.
The stub Day1Test class shows a test of the functionality of Day1 where the test input differs from the actual input.


  • Inputs go into src/main/resources and follow the naming convention input_day_X.txt
  • Solutions go into src/main/kotlin/days and extend the Day abstract class, calling its constructor with their day number
  • Solutions follow the naming convention DayX
  • It is assumed all solutions will have two parts but share the same input
  • Input is exposed in the solution classes in two forms – inputList and inputString
  • Day 1 solution class and input file are stubbed as a guide on how to extend the project,
    and how you can use the inputList and inputString mentioned above
  • To get started simply replace src/main/input_day_1.txt with the real input and the solutions in Day1 with your own
  • A Day 1 test class also exists, mostly to show a few hamcrest matchers, and how test input files can differ from actual ones (see Test input section above).
    To get started with testing you can edit this class, and the input file at src/test/resources/input_day_1.txt


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