aoc-2024 - Day08

Author: Krystian Kaniowski

advent-of-code-2024/src/Day08.kt

@@ -0,0 +1,145 @@
+// https://adventofcode.com/2024/day/8
+
+data class Point2(val x: Int, val y: Int)
+
+data class Antinodes(val xSize: Int, val ySize: Int) {
+
+ val array = Array(ySize) { Array(xSize) { false } }
+
+ fun isInBounds(x: Int, y: Int) = x in 0 until xSize && y in 0 until ySize
+
+ operator fun get(x: Int, y: Int) = if (isInBounds(x, y)) array[y][x] else null
+ operator fun set(x: Int, y: Int, field: Boolean) {
+ if (isInBounds(x, y)) {
+ array[y][x] = field
+ }
+ }
+
+ fun count() = array.sumOf { it.count { it } }
+
+ fun printArray() {
+ for (y in array.indices) {
+ for (x in array[y].indices) {
+ print(if (get(x, y)!!) "#" else ".")
+ }
+ println("")
+ }
+ println("")
+ }
+}
+
+data class Antenas(val xSize: Int, val ySize: Int) {
+
+ val array = Array(ySize) { Array<Char?>(xSize) { null } }
+
+ operator fun get(x: Int, y: Int) = if (isInBounds(x, y)) array[y][x] else null
+ operator fun set(x: Int, y: Int, field: Char) {
+ array[y][x] = field
+ }
+
+ fun getPoints(): Map<Char, List<Point>> {
+ val map: MutableMap<Char, MutableSet<Point>> = mutableMapOf()
+ for (y in array.indices) {
+ for (x in array[y].indices) {
+ get(x, y)
+ ?.let { it.takeIf { it != '.' } }
+ ?.let { map[it] = map.getOrDefault(it, mutableSetOf()).apply { add(Point(x, y)) } }
+ }
+ }
+ return map.mapValues { it.value.toList() }
+ }
+
+ fun isInBounds(x: Int, y: Int) = x in 0 until xSize && y in 0 until ySize
+
+ fun printArray() {
+ for (y in array.indices) {
+ for (x in array[y].indices) {
+ print(array[y][x])
+ }
+ println("")
+ }
+ println("")
+ }
+}
+
+fun main() {
+
+ fun part1(input: List<String>): Int {
+
+ val antenas = Antenas(input[0].length, input.size)
+ val antinodes = Antinodes(input[0].length, input.size)
+
+ input.forEachIndexed { y, list ->
+ list.forEachIndexed { x, char ->
+ antenas[x, y] = char
+ }
+ }
+
+ antenas.printArray()
+
+ antenas.getPoints().forEach { (char, points) ->
+ for (i in points.indices) {
+ for (j in (i + 1) until points.size) {
+ val dx = points[i].x - points[j].x
+ val dy = points[i].y - points[j].y
+ listOf(
+ Point(points[i].x + dx, points[i].y + dy),
+ Point(points[j].x - dx, points[j].y - dy)
+ ).forEach {
+ antinodes[it.x, it.y] = true
+ }
+ }
+ }
+ }
+
+ antinodes.printArray()
+
+ return antinodes.count()
+ }
+
+ fun part2(input: List<String>): Int {
+ val antenas = Antenas(input[0].length, input.size)
+ val antinodes = Antinodes(input[0].length, input.size)
+
+ input.forEachIndexed { y, list ->
+ list.forEachIndexed { x, char ->
+ antenas[x, y] = char
+ }
+ }
+
+ antenas.printArray()
+
+ antenas.getPoints().forEach { (char, points) ->
+ for (i in points.indices) {
+ for (j in (i + 1) until points.size) {
+ val dx = points[i].x - points[j].x
+ val dy = points[i].y - points[j].y
+
+ var newPoint = Point(points[i].x, points[i].y)
+ while (antinodes.isInBounds(newPoint.x, newPoint.y)) {
+ antinodes[newPoint.x, newPoint.y] = true
+ newPoint = Point(newPoint.x + dx, newPoint.y + dy)
+ }
+
+ newPoint = Point(newPoint.x - dx, newPoint.y - dy)
+ while (antinodes.isInBounds(newPoint.x, newPoint.y)) {
+ antinodes[newPoint.x, newPoint.y] = true
+ newPoint = Point(newPoint.x - dx, newPoint.y - dy)
+ }
+ }
+ }
+ }
+
+ antinodes.printArray()
+
+ return antinodes.count()
+ }
+
+ val testInput = readInput("Day08_test")
+ val input = readInput("Day08")
+
+ test(14) { part1(testInput) }
+ exec { part1(input) }
+ test(34) { part2(testInput) }
+ exec { part2(input) }
+}