Day 03 2024 (#259)

Author: peckb1

README.md

@@ -100,6 +100,10 @@ as the value which passed the given day/phase combination
 * Day 20
   * A good reverse engineering problem, where you need to examine the input to understand the problem; without the reverse engineering logic being too hard to spot 
 
+#### 2024
+* Day 03
+  * Regex shining today! Sorting by the match location made the single list of all matches easy to scan through.
+
 ### Interesting approaches:
 
 #### 2015

src/main/kotlin/me/peckb/aoc/_2024/calendar/day03/Day03.kt

@@ -0,0 +1,45 @@
+package me.peckb.aoc._2024.calendar.day03
+
+import javax.inject.Inject
+import me.peckb.aoc.generators.InputGenerator.InputGeneratorFactory
+
+class Day03 @Inject constructor(
+  private val generatorFactory: InputGeneratorFactory,
+) {
+  fun partOne(filename: String) = generatorFactory.forFile(filename).read { lines ->
+    lines.sumOf { line ->
+      val matches = "mul\\(\\d+,\\d+\\)".toRegex().findAll(line)
+
+      matches.sumOf { match -> match.value.getMultiplicationResult() }
+    }
+  }
+
+  fun partTwo(filename: String) = generatorFactory.forFile(filename).read { lines ->
+    var enabled = true
+
+    lines.sumOf { line ->
+      val mulMatches = "mul\\(\\d+,\\d+\\)".toRegex().findAll(line)
+      val doMatches = "do\\(\\)".toRegex().findAll(line)
+      val dontMatches = "don\'t\\(\\)".toRegex().findAll(line)
+
+      val sortedMatches = (mulMatches + doMatches + dontMatches).sortedBy { it.range.first }
+
+      var count = 0L
+
+      sortedMatches.forEach { match ->
+        val value = match.value
+
+        when (value.take(3)) {
+          "do(" -> enabled = true
+          "don" -> enabled = false
+          "mul" -> if (enabled) { count += value.getMultiplicationResult() }
+        }
+      }
+
+      count
+    }
+  }
+
+  private fun String.getMultiplicationResult() =
+    this.drop(4).dropLast(1).split(",").map { it.toInt() }.reduce(Int::times)
+}

src/main/kotlin/me/peckb/aoc/_2024/calendar/day03/README.md

@@ -0,0 +1 @@
+## [Day 3: Mull It Over](https://adventofcode.com/2024/day/3)

src/test/kotlin/me/peckb/aoc/_2024/TestDayComponent.kt

@@ -2,6 +2,7 @@ package me.peckb.aoc._2024
 
 import dagger.Component
 import me.peckb.aoc._2024.calendar.day02.Day02Test
+import me.peckb.aoc._2024.calendar.day03.Day03Test
 import javax.inject.Singleton
 import me.peckb.aoc.DayComponent
 import me.peckb.aoc.InputModule
@@ -12,4 +13,5 @@ import me.peckb.aoc._2024.calendar.day01.Day01Test
 internal interface TestDayComponent : DayComponent {
   fun inject(day01Test: Day01Test)
   fun inject(day02Test: Day02Test)
+  fun inject(day03Test: Day03Test)
 }

src/test/kotlin/me/peckb/aoc/_2024/calendar/day03/Day03Test.kt

@@ -0,0 +1,32 @@
+package me.peckb.aoc._2024.calendar.day03
+
+import javax.inject.Inject
+
+import me.peckb.aoc._2024.DaggerTestDayComponent
+import org.junit.jupiter.api.Assertions.assertEquals
+import org.junit.jupiter.api.BeforeEach
+import org.junit.jupiter.api.Test
+
+internal class Day03Test {
+  @Inject
+  lateinit var day03: Day03
+
+  @BeforeEach
+  fun setup() {
+    DaggerTestDayComponent.create().inject(this)
+  }
+
+  @Test
+  fun testDay03PartOne() {
+    assertEquals(173517243, day03.partOne(DAY_03))
+  }
+
+  @Test
+  fun testDay03PartTwo() {
+    assertEquals(100450138, day03.partTwo(DAY_03))
+  }
+
+  companion object {
+    private const val DAY_03: String = "advent-of-code-input/2024/day03.input"
+  }
+}