Day 13

day13/part1.kts

@@ -0,0 +1,56 @@
+#!/usr/bin/env kotlin
+
+import java.io.File
+import kotlin.math.floor
+
+// I LOVE MATH
+typealias Matrix2 = Pair<Pair<Int, Int>, Pair<Int, Int>>
+fun Matrix2.determinant(): Int = (this.first.first * this.second.second) - (this.first.second * this.second.first)
+
+typealias Point = Pair<Int, Int>
+
+data class Game(
+    val buttonA: Point,
+    val buttonB: Point,
+    val goal: Point
+)
+
+val games = File("input.txt").readLines().chunked(4).map { lines ->
+    Game(
+        buttonA = lines[0].substring(12).split(", Y+").let {
+            it[0].toInt() to it[1].toInt()
+        },
+        buttonB = lines[1].substring(12).split(", Y+").let {
+            it[0].toInt() to it[1].toInt()
+        },
+        goal = lines[2].substring(9).split(", Y=").let {
+            it[0].toInt() to it[1].toInt()
+        }
+    )
+}
+
+var tokens = 0
+
+games.forEach { game ->
+    val aPresses = Matrix2(
+        game.goal.first to game.buttonB.first,
+        game.goal.second to game.buttonB.second
+    ).determinant().toDouble() / Matrix2(
+        game.buttonA.first to game.buttonB.first,
+        game.buttonA.second to game.buttonB.second
+    ).determinant()
+
+    val bPresses = Matrix2(
+        game.buttonA.first to game.goal.first,
+        game.buttonA.second to game.goal.second
+    ).determinant().toDouble() / Matrix2(
+        game.buttonA.first to game.buttonB.first,
+        game.buttonA.second to game.buttonB.second
+    ).determinant()
+
+    if (aPresses != floor(aPresses) || bPresses != floor(bPresses)) return@forEach
+
+    tokens += aPresses.toInt() * 3 + bPresses.toInt()
+}
+
+println("Result: $tokens")

day13/part2.kts

@@ -0,0 +1,58 @@
+#!/usr/bin/env kotlin
+
+import java.io.File
+import kotlin.math.floor
+
+// I LOVE MATH
+typealias Matrix2 = Pair<Pair<Long, Long>, Pair<Long, Long>>
+fun Matrix2.determinant(): Long = (this.first.first * this.second.second) - (this.first.second * this.second.first)
+
+typealias Point = Pair<Long, Long>
+
+data class Game(
+    val buttonA: Point,
+    val buttonB: Point,
+    val goal: Point
+)
+
+val games = File("input.txt").readLines().chunked(4).map { lines ->
+    Game(
+        buttonA = lines[0].substring(12).split(", Y+").let {
+            it[0].toLong() to it[1].toLong()
+        },
+        buttonB = lines[1].substring(12).split(", Y+").let {
+            it[0].toLong() to it[1].toLong()
+        },
+        goal = lines[2].substring(9).split(", Y=").let {
+            it[0].toLong() + 10000000000000 to it[1].toLong() + 10000000000000
+        }
+    )
+}
+
+var tokens = 0L
+
+games.forEach { game ->
+    val aPressesNumer = Matrix2(
+        game.goal.first to game.buttonB.first,
+        game.goal.second to game.buttonB.second
+    ).determinant()
+    val aPressesDenom = Matrix2(
+        game.buttonA.first to game.buttonB.first,
+        game.buttonA.second to game.buttonB.second
+    ).determinant()
+
+    val bPressesNumer = Matrix2(
+        game.buttonA.first to game.goal.first,
+        game.buttonA.second to game.goal.second
+    ).determinant()
+    val bPressesDenom = Matrix2(
+        game.buttonA.first to game.buttonB.first,
+        game.buttonA.second to game.buttonB.second
+    ).determinant()
+
+    if (aPressesNumer % aPressesDenom == 0L && bPressesNumer % bPressesDenom == 0L) {
+        tokens += (aPressesNumer / aPressesDenom) * 3 + (bPressesNumer / bPressesDenom)
+    }
+}
+
+println("Result: $tokens")