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Day 15 2024 (#275)
Day 15 2024
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‎src/main/kotlin/me/peckb/aoc/_2024/calendar/day15/Day15.kt‎

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package me.peckb.aoc._2024.calendar.day15
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import javax.inject.Inject
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import me.peckb.aoc.generators.InputGenerator.InputGeneratorFactory
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class Day15 @Inject constructor(
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private val generatorFactory: InputGeneratorFactory,
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) {
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fun partOne(filename: String) = generatorFactory.forFile(filename).read { input ->
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var gx = -1
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var gy = -1
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val area = mutableListOf<MutableList<Room>>()
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val directions = mutableListOf<Direction>()
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var setupArea = true
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input.forEachIndexed setup@ { yIndex, line ->
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if (line.isEmpty()) {
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setupArea = false
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return@setup
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}
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if (setupArea) {
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val row = mutableListOf<Room>()
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line.forEachIndexed { xIndex, c ->
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when (c) {
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'#' -> row.add(Room.WALL)
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'.' -> row.add(Room.EMPTY)
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'O' -> row.add(Room.BOX)
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else -> {
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row.add(Room.GUARD)
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gx = xIndex
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gy = yIndex
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}
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}
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}
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area.add(row)
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} else {
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line.forEach { c ->
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when (c) {
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'<' -> directions.add(Direction.W)
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'^' -> directions.add(Direction.N)
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'>' -> directions.add(Direction.E)
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else -> directions.add(Direction.S)
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}
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}
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}
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}
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directions.forEach { direction ->
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val (yDelta, xDelta) = when (direction) {
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Direction.N -> -1 to 0
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Direction.E -> 0 to 1
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Direction.S -> 1 to 0
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Direction.W -> 0 to -1
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}
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var boxes = 1
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var boxEnd = area[gy + (yDelta * boxes)][gx + (xDelta * boxes)]
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while (boxEnd == Room.BOX) {
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boxes++
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boxEnd = area[gy + (yDelta * boxes)][gx + (xDelta * boxes)]
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}
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boxes--
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if (boxEnd == Room.EMPTY) {
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while (boxes > 0) {
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area[gy + (yDelta * (boxes + 1))][gx + (xDelta * (boxes + 1))] = Room.BOX
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boxes--
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}
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area[gy][gx] = Room.EMPTY
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gx += xDelta
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gy += yDelta
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area[gy][gx] = Room.GUARD
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}
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}
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area.withIndex().sumOf { (y, row) ->
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row.withIndex().sumOf { (x, room) ->
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when (room) {
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Room.BOX -> (100 * y) + x
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else -> 0
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}
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}
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}
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}
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fun partTwo(filename: String) = generatorFactory.forFile(filename).read { input ->
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var guard: WideRoom = WideRoom.Guard(-1, -1)
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val area = mutableListOf<MutableList<WideRoom>>()
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val directions = mutableListOf<Direction>()
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var setupArea = true
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input.forEachIndexed setup@ { y, line ->
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if (line.isEmpty()) {
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setupArea = false
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return@setup
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}
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if (setupArea) {
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val row = mutableListOf<WideRoom>()
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line.forEachIndexed { x, c ->
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val x1 = x*2
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val x2 = x*2 + 1
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when (c) {
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'#' -> {
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row.add(WideRoom.Wall(y, x1))
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row.add(WideRoom.Wall(y, x2))
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}
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'.' -> {
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row.add(WideRoom.Empty(y, x1))
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row.add(WideRoom.Empty(y, x2))
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}
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'O' -> {
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row.add(WideRoom.LeftBox(y, x1))
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row.add(WideRoom.RightBox(y, x2))
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}
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else -> {
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row.add(WideRoom.Guard(y, x1).also { guard = it })
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row.add(WideRoom.Empty(y, x2))
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}
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}
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}
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area.add(row)
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} else {
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line.forEach { c ->
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when (c) {
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'<' -> directions.add(Direction.W)
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'^' -> directions.add(Direction.N)
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'>' -> directions.add(Direction.E)
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else -> directions.add(Direction.S)
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}
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}
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}
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}
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directions.forEach { direction ->
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if (direction == Direction.W || direction == Direction.E) {
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val xDelta = when (direction) {
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Direction.E -> 1
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Direction.W -> -1
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else -> throw IllegalStateException("can't move N/S in an E/W block")
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}
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var boxes = 1
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var boxEnd = area[guard.y][guard.x + (xDelta * boxes)]
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while (boxEnd is WideRoom.RightBox || boxEnd is WideRoom.LeftBox) {
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boxes++
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boxEnd = area[guard.y][guard.x + (xDelta * boxes)]
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}
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boxes--
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if (boxEnd is WideRoom.Empty) {
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while (boxes > 0) {
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val x = guard.x + (xDelta * (boxes + 1))
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area[guard.y][x] = area[guard.y][guard.x + (xDelta * boxes)].also { it.x = x }
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boxes--
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}
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area[guard.y][guard.x] = WideRoom.Empty(guard.y, guard.x)
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guard.x += xDelta
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area[guard.y][guard.x] = guard
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}
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} else { // N/S Block!
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val yDelta = when (direction) {
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Direction.N -> -1
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Direction.S -> 1
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else -> throw IllegalStateException("can't move N/S in an E/W block")
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}
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var allCanMove = true
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var doneSearching = false
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val areasToMove = mutableMapOf<Int, Set<WideRoom>>()
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areasToMove[guard.y] = setOf(area[guard.y][guard.x])
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var currentY = guard.y
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while(allCanMove && !doneSearching) {
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areasToMove[currentY]?.forEach { room ->
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when (val nextArea = area[room.y + yDelta][room.x]) {
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is WideRoom.Wall -> allCanMove = false
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is WideRoom.LeftBox -> {
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areasToMove.merge(currentY + yDelta, setOf(nextArea)) { a, b -> a + b }
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areasToMove.merge(currentY + yDelta, setOf(area[room.y + yDelta][room.x + 1])) { a, b -> a + b }
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}
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is WideRoom.RightBox -> {
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areasToMove.merge(currentY + yDelta, setOf(nextArea)) { a, b -> a + b }
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areasToMove.merge(currentY + yDelta, setOf(area[room.y + yDelta][room.x - 1])) { a, b -> a + b }
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}
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else -> { /* ignore empty rooms */ }
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}
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} ?: run { doneSearching = true }
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currentY += yDelta
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}
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if (allCanMove) {
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val sortedEntries = areasToMove.entries.sortedBy { it.key }
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.let { if (direction == Direction.S) { it.reversed() } else { it } }
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sortedEntries.forEach { (y, wideRooms) ->
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wideRooms.forEach { room ->
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if (areasToMove[y - yDelta]?.contains(area[room.y - yDelta][room.x]) != true) {
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area[room.y][room.x] = WideRoom.Empty(room.y - yDelta, room.x)
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}
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room.y += yDelta
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area[room.y][room.x] = room
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}
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}
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}
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}
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}
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area.withIndex().sumOf { (y, row) ->
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row.withIndex().sumOf { (x, room) ->
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when (room) {
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is WideRoom.LeftBox -> (100 * y) + x
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else -> 0
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}
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}
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}
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}
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}
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enum class Room(val c: Char) {
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EMPTY('.'), WALL('#'), BOX('O'), GUARD('@');
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override fun toString(): String { return c.toString() }
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}
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sealed class WideRoom(val c: Char, var y: Int, var x: Int) {
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class Empty(y: Int, x: Int) : WideRoom('.', y, x)
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class Guard(y: Int, x: Int) : WideRoom('@', y, x)
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class Wall(y: Int, x: Int) : WideRoom('#', y, x)
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class LeftBox(y: Int, x: Int) : WideRoom('[', y, x)
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class RightBox(y: Int, x: Int) : WideRoom(']', y, x)
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override fun toString(): String { return c.toString() }
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}
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enum class Direction { N,E,S,W }

‎src/main/kotlin/me/peckb/aoc/_2024/calendar/day15/README.md‎

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## [Day 15: Warehouse Woes](https://adventofcode.com/2024/day/15)

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

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import me.peckb.aoc._2024.calendar.day12.Day12Test
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import me.peckb.aoc._2024.calendar.day13.Day13Test
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import me.peckb.aoc._2024.calendar.day14.Day14Test
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import me.peckb.aoc._2024.calendar.day15.Day15Test
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import javax.inject.Singleton
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import me.peckb.aoc.DayComponent
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import me.peckb.aoc.InputModule
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fun inject(day12Test: Day12Test)
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fun inject(day13Test: Day13Test)
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fun inject(day14Test: Day14Test)
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fun inject(day15Test: Day15Test)
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}

‎src/test/kotlin/me/peckb/aoc/_2024/calendar/day15/Day15Test.kt‎

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package me.peckb.aoc._2024.calendar.day15
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import javax.inject.Inject
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import me.peckb.aoc._2024.DaggerTestDayComponent
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import org.junit.jupiter.api.Assertions.assertEquals
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import org.junit.jupiter.api.BeforeEach
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import org.junit.jupiter.api.Test
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internal class Day15Test {
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@Inject
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lateinit var day15: Day15
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@BeforeEach
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fun setup() {
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DaggerTestDayComponent.create().inject(this)
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}
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@Test
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fun testDay15PartOne() {
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assertEquals(1475249, day15.partOne(DAY_15))
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}
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@Test
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fun testDay15PartTwo() {
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assertEquals(1509724, day15.partTwo(DAY_15))
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}
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companion object {
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private const val DAY_15: String = "advent-of-code-input/2024/day15.input"
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}
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}

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