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Mistborn94Mistborn94
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Solve day 15
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‎src/main/kotlin/day15/Day15.kt

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package day15
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import helper.Debug
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import helper.point.Direction
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import helper.point.base.Point
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import helper.point.base.get
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import helper.point.base.indexOf
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import helper.point.base.points
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import helper.removeFirst
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import kotlin.collections.component1
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import kotlin.collections.component2
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fun solveA(text: String, debug: Debug = Debug.Disabled): Int {
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val (mapText, instructionsText) = text.split("\n\n")
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val map = mapText.lines()
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val instructions = instructionsText.replace("\n", "")
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val walls = mutableSetOf<Point>()
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val boxes = mutableSetOf<Point>()
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var robot = map.indexOf('@')
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map.points().forEach { p ->
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val c = map[p]
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when (c) {
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'#' -> walls += p
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'O' -> boxes += p
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}
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}
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instructions.forEach { c ->
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val direction = when (c) {
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'<' -> Direction.LEFT
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'>' -> Direction.RIGHT
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'^' -> Direction.UP
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'v' -> Direction.DOWN
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else -> TODO("Unknown direction $c")
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}
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val nextPoint = robot + direction.point
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if (nextPoint !in walls && nextPoint !in boxes) {
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robot = nextPoint
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} else {
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val boxesToMove = mutableSetOf<Point>()
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var nextBox = nextPoint
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while (nextBox in boxes) {
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boxesToMove.add(nextBox)
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nextBox += direction.point
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}
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if (nextBox !in walls) {
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boxes.removeAll(boxesToMove)
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boxes.addAll(boxesToMove.map { it + direction.point })
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robot = nextPoint
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}
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}
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}
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return boxes.sumOf { (x, y) -> x + y * 100 }
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}
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fun solveB(text: String, debug: Debug = Debug.Disabled): Int {
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val (mapText, instructionsText) = text.split("\n\n")
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val map = mapText.lines()
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val width = map[0].length * 2
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val height = map.size
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val instructions = instructionsText.replace("\n", "")
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val walls = mutableSetOf<Point>()
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val boxes = mutableSetOf<Pair<Point, Point>>()
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var robot = map.indexOf('@').let { (x, y) -> Point(x * 2, y) }
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map.points().forEach { p ->
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val p1 = Point(p.x * 2, p.y)
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val p2 = Point(p.x * 2 + 1, p.y)
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val c = map[p]
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when (c) {
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'#' -> {
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walls += p1
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walls += p2
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}
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'O' -> {
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boxes.add(p1 to p2)
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}
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}
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}
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debug {
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println("Initial State:")
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printMap(height, width, robot, walls, boxes)
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}
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instructions.forEachIndexed { i, c ->
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val direction = when (c) {
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'<' -> Direction.LEFT
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'>' -> Direction.RIGHT
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'^' -> Direction.UP
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'v' -> Direction.DOWN
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else -> throw IllegalArgumentException("Unknown direction $c")
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}
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val boxesToMove = mutableSetOf<Pair<Point, Point>>()
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val pointsToVisit = mutableSetOf(robot + direction.point)
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while (pointsToVisit.isNotEmpty() && pointsToVisit.first() !in walls) {
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val nextBoxPoint = pointsToVisit.removeFirst()
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val possibleBoxes = setOf(
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Pair(nextBoxPoint + Direction.LEFT.point, nextBoxPoint),
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Pair(nextBoxPoint, nextBoxPoint + Direction.RIGHT.point)
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)
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val box = possibleBoxes.firstOrNull { it in boxes }
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if (box != null) {
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boxesToMove.add(box)
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when (direction) {
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Direction.UP, Direction.DOWN -> {
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pointsToVisit.add(box.first + direction.point)
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pointsToVisit.add(box.second + direction.point)
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}
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Direction.LEFT -> pointsToVisit.add(box.first + direction.point)
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else -> pointsToVisit.add(box.second + direction.point)
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}
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}
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}
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if (pointsToVisit.none { it in walls }) {
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boxes.removeAll(boxesToMove)
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boxes.addAll(boxesToMove.map { (first, second) -> first + direction.point to second + direction.point })
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robot += direction.point
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}
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debug {
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println("Movement $c ($i):")
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printMap(height, width, robot, walls, boxes)
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}
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}
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return boxes.map { it.first }.sumOf { (x, y) -> x + y * 100 }
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}
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private fun printMap(
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height: Int,
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width: Int,
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robot: Point,
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walls: Set<Point>,
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boxes: Set<Pair<Point, Point>>
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) {
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repeat(height) { y ->
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repeat(width) { x ->
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val point = Point(x, y)
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val boxL = Pair(point, point + Direction.RIGHT.point)
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val boxR = Pair(point + Direction.LEFT.point, point)
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when {
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point == robot -> print('@')
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point in walls -> print('#')
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boxL in boxes -> print('[')
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boxR in boxes -> print(']')
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else -> print('.')
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}
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}
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println()
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}
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println()
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}

‎src/main/resources/inputs

‎src/test/kotlin/day15/Day15KtTest.kt

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package day15
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import helper.Debug
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import helper.readDayFile
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import kotlin.test.Test
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import kotlin.test.assertEquals
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internal class Day15KtTest {
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private val day = 15
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@Test
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fun sample1() {
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val text = """
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##########
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#..O..O.O#
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#......O.#
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#.OO..O.O#
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#..O@..O.#
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#O#..O...#
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#O..O..O.#
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#.OO.O.OO#
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#....O...#
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##########
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<vv>^<v^>v>^vv^v>v<>v^v<v<^vv<<<^><<><>>v<vvv<>^v^>^<<<><<v<<<v^vv^v>^
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vvv<<^>^v^^><<>>><>^<<><^vv^^<>vvv<>><^^v>^>vv<>v<<<<v<^v>^<^^>>>^<v<v
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><>vv>v^v^<>><>>>><^^>vv>v<^^^>>v^v^<^^>v^^>v^<^v>v<>>v^v^<v>v^^<^^vv<
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<<v<^>>^^^^>>>v^<>vvv^><v<<<>^^^vv^<vvv>^>v<^^^^v<>^>vvvv><>>v^<<^^^^^
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^><^><>>><>^^<<^^v>>><^<v>^<vv>>v>>>^v><>^v><<<<v>>v<v<v>vvv>^<><<>^><
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^>><>^v<><^vvv<^^<><v<<<<<><^v<<<><<<^^<v<^^^><^>>^<v^><<<^>>^v<v^v<v^
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>^>>^v>vv>^<<^v<>><<><<v<<v><>v<^vv<<<>^^v^>^^>>><<^v>>v^v><^^>>^<>vv^
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<><^^>^^^<><vvvvv^v<v<<>^v<v>v<<^><<><<><<<^^<<<^<<>><<><^^^>^^<>^>v<>
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^^>vv<^v^v<vv>^<><v<^v>^^^>>>^^vvv^>vvv<>>>^<^>>>>>^<<^v>^vvv<>^<><<v>
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v^^>>><<^^<>>^v^<v^vv<>v^<<>^<^v^v><^<<<><<^<v><v<>vv>>v><v^<vv<>v^<<^
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""".trimIndent().trimEnd()
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assertEquals(10092, solveA(text, Debug.Disabled))
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assertEquals(9021, solveB(text, Debug.Disabled))
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}
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@Test
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fun sample2() {
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// val text = readDayFile(day, "sample2.in").readText().trimEnd()
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val text = """
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########
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#..O.O.#
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##@.O..#
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#...O..#
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#.#.O..#
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#...O..#
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#......#
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########
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<^^>>>vv<v>>v<<
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""".trimIndent().trimEnd()
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assertEquals(2028, solveA(text, Debug.Disabled))
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}
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@Test
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fun sample3() {
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// val text = readDayFile(day, "sample2.in").readText().trimEnd()
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val text = """
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#######
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#...#.#
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#.....#
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#..OO@#
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#..O..#
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#.....#
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#######
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<vv<<^^<<^^
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""".trimIndent().trimEnd()
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assertEquals(618, solveB(text, Debug.Enabled))
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}
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@Test
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fun solve() {
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val lines = readDayFile(day, "input").readText().trimEnd()
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val solveA = solveA(lines)
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println("A: $solveA")
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assertEquals(1552879, solveA)
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val solveB = solveB(lines)
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println("B: $solveB")
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assertEquals(1561175, solveB)
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}
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}

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