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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -1,124 +1,91 @@ | ||
| package no.rodland.advent_2024 | ||
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| import no.rodland.advent.Day | ||
| import no.rodland.advent.Direction | ||
| import no.rodland.advent.Pos | ||
| import kotlin.math.abs | ||
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| // template generated: 12/12/2024 | ||
| // Fredrik Rødland 2024 | ||
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| class Day12(val input: List<String>) : Day<Int, Int, Pair<Array<CharArray>, Array<CharArray>>> { | ||
| class Day12(val input: List<String>) : Day<Int, Int, Array<CharArray>> { | ||
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| private val parsed = input.parse() | ||
| private val grid = parsed.first | ||
| private val rotated = parsed.second | ||
| private val grid = input.parse() | ||
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| data class Region(val c: Char, val positions: Set<Pos>) { | ||
| operator fun contains(pos: Pos): Boolean = pos in positions | ||
| fun area() = positions.size | ||
| fun neighbours() = positions.flatMap { it.neighbourCellsUDLR() }.filterNot { it in positions } | ||
| fun perimeter(): Int = neighbours().size | ||
| } | ||
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| override fun partOne(): Int { | ||
| return findAllRegions().sumOf { | ||
| it.area() * it.perimeter() | ||
| return findAllRegions().sumOf { region -> | ||
| region.area() * region.perimeter() | ||
| } | ||
| } | ||
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| override fun partTwo(): Int { | ||
| return findAllRegions().sumOf { region -> | ||
| region.sides() * region.area() | ||
| } | ||
| } | ||
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| private fun Region.sides(): Int { | ||
| return positions.sumOf { p -> p.corners() } | ||
| } | ||
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| // got help from: https://todd.ginsberg.com/post/advent-of-code/2024/day12/ | ||
| private fun Pos.corners(): Int { | ||
| val c = grid[this] | ||
| return listOf(Direction.NORTH, Direction.EAST, Direction.SOUTH, Direction.WEST, Direction.NORTH) | ||
| .zipWithNext() | ||
| .map { (first, second) -> | ||
| listOf( | ||
| grid[next(first)], | ||
| grid[next(second)], | ||
| grid[next(first).next(second)] | ||
| ) | ||
| }.count { (side1, side2, corner) -> | ||
| (c != side1 && c != side2) || (side1 == c && side2 == c && corner != c) | ||
| } | ||
| } | ||
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| @Suppress("ConvertCallChainIntoSequence") | ||
| private fun findAllRegions(): List<Region> { | ||
| fun getRegion(grid: Grid, pos: Pos, visited: MutableSet<Pos>): Set<Pos> { | ||
| return (setOf(pos) + pos.neighbourCellsUDLR() | ||
| .filter { it !in visited } | ||
| .filter { it in this@Day12.grid } | ||
| .filter { this@Day12.grid[it] == this@Day12.grid[pos] } | ||
| .onEach { visited.add(it) } | ||
| .flatMap { getRegion(grid, it, visited) } | ||
| .toList()).toSet() | ||
| } | ||
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| val visited = mutableSetOf<Pos>() | ||
| return grid.flatMapIndexed { y, row -> | ||
| row.mapIndexed { x, c -> | ||
| val pos = Pos(x, y) | ||
| if (pos !in visited) { | ||
| Region(c, grid.getRegion(pos, visited)) | ||
| Region(c, getRegion(grid, pos, visited)) | ||
| } else { | ||
| null | ||
| } | ||
| }.filterNotNull() | ||
| } | ||
| } | ||
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| @Suppress("ConvertCallChainIntoSequence") | ||
| private fun Array<CharArray>.getRegion(pos: Pos, visited: MutableSet<Pos>): Set<Pos> { | ||
| return (setOf(pos) + pos.neighbourCellsUDLR() | ||
| .filter { it !in visited } | ||
| .filter { it in grid } | ||
| .filter { grid[it] == grid[pos] } | ||
| .onEach { visited.add(it) } | ||
| .flatMap { getRegion(it, visited) } | ||
| .toList()).toSet() | ||
| } | ||
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| override fun partTwo(): Int { | ||
| val regions = findAllRegions() | ||
| // regions.forEach { println(it.toString() + ": " + it.neighbours()) } | ||
| // | ||
| // val initMaybe = regions[0].neighbours().map { setOf(it) } | ||
| // val test0 = regions[0].neighbours().fold(initMaybe) { acc: List<Set<Pos>>, pos: Pos -> | ||
| // val (fences, rest) = acc.partition { fence -> fence.sameFence(pos) } | ||
| // if (fences.isEmpty()) { | ||
| // rest | ||
| // } else { | ||
| // (rest + fences.map { it + pos }).filterNot { it == setOf(pos) } | ||
| // } | ||
| // }.map { it.sorted() }.toSet() | ||
| return 2 | ||
| } | ||
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| private fun Set<Pos>.sameFence(pos: Pos): Boolean { | ||
| return if (size == 0) { | ||
| error("should not happen") | ||
| } else { | ||
| val first = first() | ||
| if (first == pos) { | ||
| true | ||
| } else if (size == 1) { | ||
| first.isAdjacent(pos) | ||
| } else if (all { it.x == first.x }) { | ||
| any { it.isAdjacentY(pos) } | ||
| } else if (all { it.y == first.y }) { | ||
| any { it.isAdjacentX(pos) } | ||
| } else { | ||
| error("should not happen either") | ||
| } | ||
| } | ||
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| TODO("Not yet implemented") | ||
| } | ||
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| fun Pos.isAdjacent(other: Pos) = abs(x - other.x) + abs(y - other.y) == 1 | ||
| fun Pos.isAdjacentX(other: Pos) = abs(x - other.x) == 1 && y == other.y | ||
| fun Pos.isAdjacentY(other: Pos) = abs(y - other.y) == 1 && x == other.x | ||
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| operator fun Grid.contains(pos: Pos): Boolean = pos.x >= 0 && pos.x < this[0].size && pos.y >= 0 && pos.y < this.size | ||
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| operator fun Grid.get(pos: Pos): Char = this[pos.y][pos.x] | ||
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| override fun List<String>.parse(): Pair<Array<CharArray>, Array<CharArray>> { | ||
| val upright = indices.map { y -> indices.map { x -> this[y][x] }.toCharArray() }.toTypedArray() | ||
| val rotated = indices.map { y -> indices.map { x -> this[x][y] }.toCharArray() }.toTypedArray() | ||
| return upright to rotated | ||
| } | ||
| operator fun Grid.get(pos: Pos): Char? = if (pos in this) grid[pos.y][pos.x] else null | ||
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| override fun List<String>.parse(): Grid = indices.map { y -> indices.map { x -> this[y][x] }.toCharArray() }.toTypedArray<CharArray>() | ||
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| override val day = "12".toInt() | ||
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| // private fun Grid.fences(): Int { | ||
| // flatMap { row -> | ||
| // val windowed = row.toList().windowed(2).map { (c1, c2) -> | ||
| // if (c1 == c2) 0 else 2 | ||
| // } | ||
| // windowed | ||
| // } | ||
| // return 2 | ||
| // } | ||
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| data class Region(val c: Char, val positions: Set<Pos>) { | ||
| operator fun contains(pos: Pos): Boolean = pos in positions | ||
| fun area() = positions.size | ||
| fun neighbours() = positions.flatMap { it.neighbourCellsUDLR() }.filterNot { it in positions } | ||
| fun perimeter(): Int = neighbours().size | ||
| } | ||
| } | ||
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