2024 - Day 12 - part 1

src/main/kotlin/no/rodland/advent_2024/Day12.kt

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+package no.rodland.advent_2024
+
+import no.rodland.advent.Day
+import no.rodland.advent.Pos
+
+// template generated: 12/12/2024
+// Fredrik Rødland 2024
+
+class Day12(val input: List<String>) : Day<Int, Int, Pair<Array<CharArray>, Array<CharArray>>> {
+
+    private val parsed = input.parse()
+    private val grid = parsed.first
+    private val rotated = parsed.second
+
+    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
+    }
+
+    override fun partOne(): Int {
+        return findAllRegions().sumOf {
+            it.area() * it.perimeter()
+        }
+    }
+
+    private fun findAllRegions(): List<Region> {
+        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))
+                } else {
+                    null
+                }
+            }.filterNotNull()
+        }
+    }
+
+    @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()
+    }
+
+
+    override fun partTwo(): Int {
+        return 2
+    }
+
+    operator fun Grid.contains(pos: Pos): Boolean = pos.x >= 0 && pos.x < this[0].size && pos.y >= 0 && pos.y < this.size
+
+    operator fun Grid.get(pos: Pos): Char = this[pos.y][pos.x]
+
+    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
+    }
+
+
+    override val day = "12".toInt()
+
+//    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
+//    }
+
+
+}
+
+

src/test/kotlin/no/rodland/advent_2024/Day12Test.kt

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+package no.rodland.advent_2024
+
+import no.rodland.advent.*
+import org.junit.jupiter.api.Nested
+import org.junit.jupiter.api.Test
+import readFile
+
+//
+//  run: download_aoc_input.sh to download input
+//
+
+@Suppress("ClassName")
+@DisableSlow
+internal class Day12Test {
+    private val data12 = "2024/input_12.txt".readFile()
+    private val test12 = "2024/input_12_test.txt".readFile()
+
+    private val resultTestOne = 1930
+    private val resultTestTwo = 2
+    private val resultOne = 1424472
+    private val resultTwo = 2
+
+    val test = defaultTestSuiteParseOnInit(
+        Day12(data12),
+        Day12(test12),
+        resultTestOne,
+        resultOne,
+        resultTestTwo,
+        resultTwo,
+        { Day12(data12) },
+        { Day12(test12) },
+        numTestPart1 = 5
+    )
+
+    @Nested
+    inner class Init {
+        @Test
+        fun `12,-,example,1`() {
+            report(AOCTest({ "123".toInt() }, Unit, 123, 5, "12".toInt(), Part.TWO, false, "example"))
+        }
+
+        @Test
+        fun `12,-,example,2`() {
+            report(test.initTest.copy())
+        }
+
+        @Test
+        fun `12,-,test,init`() {
+            report(test.initTest)
+        }
+
+        @Test
+        fun `12,-,live,init`() {
+            report(test.initLive)
+        }
+    }
+
+    @Nested
+    inner class `Part 1` {
+        @Test
+        fun `12,1,test`() {
+            report(test.testPart1)
+        }
+
+        @Test
+        fun `12,1,live,1`() {
+            report(test.livePart1)
+        }
+    }
+
+    @Nested
+    inner class `Part 2` {
+        @Test
+        fun `12,2,test`() {
+            report(test.testPart2)
+        }
+
+        @Test
+        fun `12,2,live,1`() {
+            report(test.livePart2)
+        }
+    }
+}

src/test/resources/2024/input_12_test.txt

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+RRRRIICCFF
+RRRRIICCCF
+VVRRRCCFFF
+VVRCCCJFFF
+VVVVCJJCFE
+VVIVCCJJEE
+VVIIICJJEE
+MIIIIIJJEE
+MIIISIJEEE
+MMMISSJEEE