2023 - Day 22 - input

src/main/kotlin/no/rodland/advent/SpacePos.kt

@@ -5,6 +5,8 @@ import kotlin.math.*
 internal const val ACTIVE = '#'
 private fun Char.active() = this == ACTIVE
 
+typealias Point = Pos
+
 sealed class SpacePos {
     abstract fun neighbours(): List<SpacePos>
     abstract fun manhattan(): Int

src/main/kotlin/no/rodland/advent_2023/Day21.kt

@@ -1,6 +1,7 @@
 package no.rodland.advent_2023
 
 import no.rodland.advent.Day
+import no.rodland.advent.Point
 import no.rodland.advent.Pos
 
 
@@ -9,8 +10,66 @@ import no.rodland.advent.Pos
 
 class Day21(val input: List<String>) : Day<Int, Long, Map<Pos, Char>> {
 
+
     private val parsed = input.parse()
+    private val width = parsed.keys.maxOf { it.x } + 1
+    private val height = parsed.keys.maxOf { it.y } + 1
+
+
+
+
+    // https://github.com/eagely/adventofcode/blob/main/src/main/kotlin/solutions/y2023/Day21.kt
+    fun solvePart2(): Any {
+        if (parsed.size < 50) return "womp womp"
+        val req = 26501365L
+        var delta = 0L
+        var skip = 0L
+        val queue = ArrayDeque<Pair<Point, Long>>()
+        val start = parsed.filterValues { it == 'S' }.keys.single()
 
+        queue.add(Pair(start, 0))
+        val visited = hashSetOf<Point>()
+        val size = Point(height, width)
+        val cycle = size.x * 2
+        var lastStep = 0L
+        var previousPlots = 0L
+        var delta1 = 0L
+        var delta2 = 0L
+        var plots = 0L
+        while (queue.isNotEmpty()) {
+            val (position, step) = queue.removeFirst()
+            if (position in visited) continue
+            if (step % 2 == 1L) visited.add(position)
+            if (step % cycle == 66L && step > lastStep) {
+                println("step: $step, plots: $plots, delta1: $delta1, delta2: $delta2")
+                lastStep = step
+                if (plots - previousPlots - delta1 == delta2) {
+                    delta = plots - previousPlots + delta2
+                    skip = step - 1
+                    break
+                }
+                delta2 = (plots - previousPlots) - delta1
+                delta1 = plots - previousPlots
+                previousPlots = plots
+            }
+            plots = visited.size.toLong()
+            queue.addAll(position.neighbourCellsUDLR().filter { parsed[it % size] != '#' }.map { it to step + 1 })
+        }
+        while (skip < req) {
+            skip += cycle
+            plots += delta
+            delta += delta2
+        }
+        return plots
+    }
+
+    operator fun Pos.rem(other: Point) = Point(x pm other.x, y pm other.y)
+    operator fun Pos.rem(other: Int) = Point(x pm other, y pm other)
+    infix fun Pos.pm(other: Point) = this % other
+    infix fun Int.pm(other: Int): Int {
+        val mod = this % other
+        return if (mod < 0) mod + other else mod
+    }
     override fun partOne(): Int {
 //        val start = parsed.filterValues { it == 'S' }.map { it.key }.single()
         var newMap = parsed
@@ -31,6 +90,7 @@ class Day21(val input: List<String>) : Day<Int, Long, Map<Pos, Char>> {
 
 
     override fun partTwo(): Long {
+        println(solvePart2())
         return 2
     }
 
@@ -44,3 +104,4 @@ class Day21(val input: List<String>) : Day<Int, Long, Map<Pos, Char>> {
 
     override val day = "21".toInt()
 }
+

src/main/kotlin/no/rodland/advent_2023/Day22.kt

@@ -0,0 +1,27 @@
+package no.rodland.advent_2023
+
+import no.rodland.advent.Day
+
+// template generated: 22/12/2023
+// Fredrik Rødland 2023
+
+class Day22(val input: List<String>) : Day<Long, Long, List<String>> {
+
+    private val parsed = input.parse()
+
+    override fun partOne(): Long {
+        return 2
+    }
+
+    override fun partTwo(): Long {
+        return 2
+    }
+
+    override fun List<String>.parse(): List<String> {
+        return map { line ->
+            line
+        }
+    }
+
+    override val day = "22".toInt()
+}

src/test/kotlin/no/rodland/advent_2023/Day21Test.kt

@@ -29,7 +29,8 @@ internal class Day21Test {
         resultTwo,
         { Day21(data21) },
         { Day21(test21) },
-        numTestPart1 = 2
+        numTestPart1 = 2,
+        numTestPart2 = 1,
     )
 
     @Nested

src/test/kotlin/no/rodland/advent_2023/Day22Test.kt

@@ -0,0 +1,82 @@
+package no.rodland.advent_2023
+
+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 Day22Test {
+    private val data22 = "2023/input_22.txt".readFile()
+    private val test22 = "2023/input_22_test.txt".readFile()
+
+    private val resultTestOne = 2L
+    private val resultTestTwo = 2L
+    private val resultOne = 2L
+    private val resultTwo = 2L
+
+    val test = defaultTestSuiteParseOnInit(
+        Day22(data22),
+        Day22(test22),
+        resultTestOne,
+        resultOne,
+        resultTestTwo,
+        resultTwo,
+        { Day22(data22) },
+        { Day22(test22) },
+    )
+
+    @Nested
+    inner class Init {
+        @Test
+        fun `22,-,example,1`() {
+            report(AOCTest({ "123".toInt() }, Unit, 123, 5, "22".toInt(), Part.TWO, false, "example"))
+        }
+
+        @Test
+        fun `22,-,example,2`() {
+            report(test.initTest.copy())
+        }
+
+        @Test
+        fun `22,-,test,init`() {
+            report(test.initTest)
+        }
+
+        @Test
+        fun `22,-,live,init`() {
+            report(test.initLive)
+        }
+    }
+
+    @Nested
+    inner class `Part 1` {
+        @Test
+        fun `22,1,test`() {
+            report(test.testPart1)
+        }
+
+        @Test
+        fun `22,1,live,1`() {
+            report(test.livePart1)
+        }
+    }
+
+    @Nested
+    inner class `Part 2` {
+        @Test
+        fun `22,2,test`() {
+            report(test.testPart2)
+        }
+
+        @Test
+        fun `22,2,live,1`() {
+            report(test.livePart2)
+        }
+    }
+}