[2025/9] Movie Theater (Part 1)

Author: pfolta

README.md

@@ -29,7 +29,7 @@
 |     2022 |   ★   |   ★   |   ★   |   ★   |   ★   |   ★   |   ★   |   ★   |   ★   |   ★    |   ★    |   ★    |   ★    |        |        |        |        |        |        |        |   ☆    |        |        |        |   ☆    |    28 |
 |     2023 |   ★   |   ★   |   ★   |   ★   |   ☆   |   ★   |   ☆   |       |       |        |        |        |        |        |        |        |        |        |        |        |        |        |        |        |        |    12 |
 |     2024 |   ★   |   ★   |   ★   |   ★   |   ★   |   ★   |   ★   |   ★   |   ★   |   ★    |   ★    |   ★    |   ★    |   ★    |        |   ☆    |   ★    |   ★    |   ★    |   ★    |        |   ★    |        |        |   ☆    |    40 |
-|     2025 |   ★   |   ★   |   ★   |   ★   |   ★   |   ★   |   ★   |   ★   |       |        |        |        |   –    |   –    |   –    |   –    |   –    |   –    |   –    |   –    |   –    |   –    |   –    |   –    |   –    |    16 |
+|     2025 |   ★   |   ★   |   ★   |   ★   |   ★   |   ★   |   ★   |   ★   |   ☆   |        |        |        |   –    |   –    |   –    |   –    |   –    |   –    |   –    |   –    |   –    |   –    |   –    |   –    |   –    |    17 |
 
 ## 🛷 How to run
 
@@ -214,6 +214,7 @@ e.g. `HandyHaversacks`)*
 |                                           |   6 | [Trash Compactor](https://adventofcode.com/2025/day/6)                                                 | [[Code](src/main/kotlin/adventofcode/year2025/Day06TrashCompactor.kt)] [[Test](src/test/kotlin/adventofcode/year2025/Day06TrashCompactorSpec.kt)]                                       | `5733696195703`        | `10951882745757`                                 |
 |                                           |   7 | [Laboratories](https://adventofcode.com/2025/day/7)                                                    | [[Code](src/main/kotlin/adventofcode/year2025/Day07Laboratories.kt)] [[Test](src/test/kotlin/adventofcode/year2025/Day07LaboratoriesSpec.kt)]                                           | `1711`                 | `36706966158365`                                 |
 |                                           |   8 | [Playground](https://adventofcode.com/2025/day/8)                                                      | [[Code](src/main/kotlin/adventofcode/year2025/Day08Playground.kt)] [[Test](src/test/kotlin/adventofcode/year2025/Day08PlaygroundSpec.kt)]                                               | `135169`               | `302133440`                                      |
+|                                           |   9 | [Movie Theater](https://adventofcode.com/2025/day/9)                                                   | [[Code](src/main/kotlin/adventofcode/year2025/Day09MovieTheater.kt)] [[Test](src/test/kotlin/adventofcode/year2025/Day09MovieTheaterSpec.kt)]                                           | `4777409595`           |                                                  |
 
 ## 🕯️ Useful commands
 

src/main/kotlin/adventofcode/year2025/Day09MovieTheater.kt

@@ -0,0 +1,21 @@
+package adventofcode.year2025
+
+import adventofcode.Puzzle
+import adventofcode.PuzzleInput
+import adventofcode.common.spatial.Point2d
+import kotlin.math.absoluteValue
+
+class Day09MovieTheater(
+    customInput: PuzzleInput? = null,
+) : Puzzle(customInput) {
+    private fun parseInput() =
+        input.lines().map { line ->
+            val (x, y) = line.split(",").map(String::toLong)
+            Point2d(x, y)
+        }
+
+    override fun partOne() =
+        parseInput()
+            .let { points -> points.flatMapIndexed { index, a -> points.subList(index + 1, points.size).map { b -> a to b } } }
+            .maxOf { (a, b) -> ((b.x - a.x).absoluteValue + 1) * ((b.y - a.y).absoluteValue + 1) }
+}