Day 25: Code Chronicle

README.md

@@ -17,6 +17,7 @@ Advent of Code is an Advent calendar of small programming puzzles by [Eric Wastl
 - Day 14: [Restroom Redoubt](https://adventofcode.com/2024/day/14) -- [Day14.kt](https://github.com/andilau/advent-of-code-2024/blob/main/src/main/kotlin/days/Day14.kt)
 - Day 18: [RAM Run](https://adventofcode.com/2024/day/18) -- [Day18.kt](https://github.com/andilau/advent-of-code-2024/blob/main/src/main/kotlin/days/Day18.kt)
 - Day 22: [Monkey Market](https://adventofcode.com/2024/day/22) -- [Day22.kt](https://github.com/andilau/advent-of-code-2024/blob/main/src/main/kotlin/days/Day22.kt)
+- Day 25: [Day 25: Code Chronicle](https://adventofcode.com/2024/day/25) -- [Day25.kt](https://github.com/andilau/advent-of-code-2024/blob/main/src/main/kotlin/days/Day25.kt)
 
 ### Features
 

src/main/kotlin/days/Day25.kt

@@ -0,0 +1,37 @@
+package days
+
+@AdventOfCodePuzzle(
+    name = "Code Chronicle",
+    url = "https://adventofcode.com/2024/day/25",
+    date = Date(day = 25, year = 2024)
+)
+class Day25(val input: String) : Puzzle {
+    private val securities: List<Security> = input.split("\n\n").map { Security.from(it) }
+
+    override fun partOne(): Int = securities
+        .filterIsInstance<Security.Lock>()
+        .flatMap { key -> securities.filterIsInstance<Security.Key>().map { lock -> key to lock } }
+        .count { (lock, key) -> lock.signature.zip(key.signatur).all { (l, p) -> l + p <= 5 } }
+
+    override fun partTwo() = Unit
+
+    sealed class Security() {
+        data class Lock(val signature: List<Int>) : Security()
+        data class Key(val signatur: List<Int>) : Security()
+
+        companion object {
+            fun from(input: String): Security {
+                val lines = input.lines()
+                return when {
+                    lines.first().all { it == '#' } -> Lock(pivot(lines.drop(1)).map { it.count { it == '#' } })
+                    lines.last().all { it == '#' } -> Key(pivot(lines.dropLast(1)).map { it.count { it == '#' } })
+                    else -> error("Something else")
+                }
+            }
+
+            private fun pivot(list: List<String>): List<String> {
+                return list[0].indices.map { col -> list.map { it[col] }.joinToString("") }
+            }
+        }
+    }
+}