2022/Day 03

Author: agrison

src/main/kotlin/me/grison/aoc/Collections.kt

@@ -177,4 +177,8 @@ fun <T> List<List<T>>.iterate(dimensions: Pair<Int, Int> = dimensions()): Sequen
  for (column in 0 until columns)
  yield(p(row, column))
  }
-}
+}
+
+fun <T> List<Set<T>>.intersectAll() = this.reduce { a, b -> a.intersect(b) }
+fun <T> List<Set<T>>.unionAll() = this.reduce { a, b -> a.union(b) }
+fun List<String>.mapSet() = this.map { it.toSet() }

src/main/kotlin/me/grison/aoc/y2022/Day03.kt

@@ -2,29 +2,25 @@ package me.grison.aoc.y2022
 
 import me.grison.aoc.Day
 import me.grison.aoc.inTwo
+import me.grison.aoc.intersectAll
+import me.grison.aoc.mapSet
 
 class Day03 : Day(3, 2022) {
  override fun title() = "Rucksack Reorganization"
 
- override fun partOne() =
- inputList.sumOf { rucksack ->
- val common = commonItem(rucksack.inTwo().map { it.toSet() })
- itemPriority(common)
- }
+ override fun partOne() = solve { rucksack -> rucksack.map { it.inTwo().mapSet() } }
 
- override fun partTwo() =
- inputList
- .map { it.toSet() }
- .windowed(size = 3, step = 3)
- .sumOf { itemPriority(commonItem(it)) }
+ override fun partTwo() = solve { it.mapSet().chunked(3) }
 
- private fun commonItem(compartments: List<Set<Char>>) =
- compartments.reduce { a, b -> a.intersect(b) }.first()
+ private fun solve(inputMixer: (List<String>) -> List<List<Set<Char>>>) =
+ inputMixer(inputList).sumOf { itemPriority(it) }
 
- private fun itemPriority(item: Char): Int =
- if (item.isLowerCase()) {
- 1 + (item.code - 'a'.code)
- } else {
- 27 + (item.code - 'A'.code)
+ private fun itemPriority(compartments: List<Set<Char>>): Int =
+ compartments.intersectAll().first().let { item ->
+ if (item.isLowerCase()) {
+ 1 + (item.code - 'a'.code)
+ } else {
+ 27 + (item.code - 'A'.code)
+ }
  }
 }