Advent of Code 2021

This year I want to improve my kotlin skills. Explore new language feature, revisited concepts I already use, ...

What did I learn so far?

Day 1

• project setup of a simple kotlin project
• com.willowtreeapps.assertk:assertk-jvm:0.25 is the lib I use for unit tests all the time at work. Needed to import it.
• Array methods: copyRanged and mapIndexed

Day 2

• I like String#trimMargin() to format input strings nicely in the tests.

Day 3

• Feels like a dirty solution :) Probably should have used some kind of bitwise-operator or so.
• I liked the recursive part.

Day 4

• boardsLines.windowed(size = 6, step = 6) is a nice way to "slide" over a list with a given window size
• Longest time was building the data structure for holding results and the boards.

Day 5

• learnt what Hydrothermal vents are
• Took time to read about the Ranges in kotlin and its different operators e.g. .., until, downTo, step
  • https://kotlinlang.org/docs/ranges.html