Day20 part2 WIP

days/src/main/kotlin/Day20.kt

@@ -0,0 +1,255 @@
+package be.vandewalleh.aoc.days
+
+import be.vandewalleh.aoc.utils.input.Day
+import be.vandewalleh.aoc.utils.input.Groups
+import be.vandewalleh.aoc.utils.input.Input
+import be.vandewalleh.aoc.utils.input.createDay
+import kotlin.math.sqrt
+
+private typealias Tile = Array<CharArray>
+private typealias Grid = Array<Array<Tile>>
+
+@Day(20)
+class Day20(@Groups val input: Input<List<List<String>>>) {
+
+    private val tiles = input.value
+        .map { it[0].let { it.substring(5 until it.indexOf(':')).toInt() } to it.drop(1) }
+        .map { (id, tile) -> id to tile.map { it.toCharArray() }.toTypedArray() }
+
+    private fun Tile.sides() = sequence {
+        val tile = this@sides
+        yield(tile[0])
+        yield(tile[tile.lastIndex])
+        yield(tile[0].reversedArray())
+        yield(tile[tile.lastIndex].reversedArray())
+        yield(tile.map { it[0] }.toCharArray())
+        yield(tile.map { it[tile.lastIndex] }.toCharArray())
+        yield(tile.map { it[0] }.asReversed().toCharArray())
+        yield(tile.map { it[tile.lastIndex] }.asReversed().toCharArray())
+    }
+
+    private fun sideMatches(a: Tile, b: Tile): Boolean {
+        val aSides = a.sides()
+        val bSides = b.sides().toList()
+        aSides.forEach { aSide ->
+            bSides.forEach { bSide ->
+                if (aSide contentEquals bSide) return true
+            }
+        }
+        return false
+    }
+
+    private fun Tile.prettyPrint() {
+        val str = buildString {
+            this@prettyPrint.forEach { line ->
+                append(line.joinToString(""))
+                appendLine()
+            }
+        }
+        print(str)
+    }
+
+    private fun combine(tiles: List<Tile>) = sequence {
+        for (i in 0 until tiles.lastIndex) {
+            val a = tiles[i]
+            for (j in i + 1 until tiles.size) {
+                val b = tiles[j]
+                yield(a to b)
+            }
+        }
+    }
+
+    private fun neighbours(): Map<Int, List<Tile>> {
+        val neighbours = combine(tiles.map { it.second })
+            .filter { (a, b) -> sideMatches(a, b) }
+            .map { it.toList() }
+            .flatten()
+            .groupBy { it.map { it.toList() } }
+            .values
+
+        val map = mutableMapOf<Int, MutableList<Tile>>()
+        for (neighbour in neighbours) {
+            map.computeIfAbsent(neighbour.size) { mutableListOf() }.add(neighbour.first())
+        }
+        return map
+    }
+
+    fun part1() = neighbours()[2]!!
+        .map { tile -> tiles.find { it.second === tile }!! }
+        .map { it.first.toLong() }
+        .reduce { acc, id -> acc * id }
+
+    operator fun Array<Array<Tile?>>.get(x: Int, y: Int): Tile? {
+        if (y < 0 || y > lastIndex) return null
+        val row = get(y)
+
+        return if (x < 0 || x > row.lastIndex) null
+        else row[x]
+    }
+
+    operator fun Array<Array<Tile?>>.set(x: Int, y: Int, tile: Tile) {
+        this[y][x] = tile
+    }
+
+    private fun fillGrid(): Grid {
+        val neighboursSet = neighbours().entries.associate { it.key to it.value.toMutableSet() }
+
+        val size = sqrt(tiles.size.toDouble()).toInt()
+        val grid: Array<Array<Tile?>> = Array(size) { Array(size) { null } }
+
+        for (x in 0 until size) {
+            for (y in 0 until size) {
+                var neighboursCount = 2
+                if (x != 0 && x != size - 1) neighboursCount++
+                if (y != 0 && y != size - 1) neighboursCount++
+
+                val pos = listOf(
+                    x to y - 1,
+                    x + 1 to y,
+                    x to y + 1,
+                    x - 1 to y,
+                )
+
+                val a = pos.mapNotNull { (x, y) -> grid[x, y] }
+
+                val iterator = neighboursSet[neighboursCount]!!.iterator()
+
+                while (iterator.hasNext()) {
+                    val possibility = iterator.next()
+                    val matches = a.count { sideMatches(it, possibility) }
+                    if (matches == a.size) {
+                        grid[x, y] = possibility
+                        iterator.remove()
+                        break
+                    }
+                }
+            }
+        }
+        return grid as Grid
+    }
+
+    private fun correctGrid(grid: Grid): Grid {
+        TODO("flip / rotate every tile")
+    }
+
+    fun part2() {
+        val grid = correctGrid(fillGrid())
+        TODO("remove tile edges")
+    }
+}
+
+fun main() {
+    with(createDay<Day20>(
+        """
+            Tile 2311:
+            ..##.#..#.
+            ##..#.....
+            #...##..#.
+            ####.#...#
+            ##.##.###.
+            ##...#.###
+            .#.#.#..##
+            ..#....#..
+            ###...#.#.
+            ..###..###
+
+            Tile 1951:
+            #.##...##.
+            #.####...#
+            .....#..##
+            #...######
+            .##.#....#
+            .###.#####
+            ###.##.##.
+            .###....#.
+            ..#.#..#.#
+            #...##.#..
+
+            Tile 1171:
+            ####...##.
+            #..##.#..#
+            ##.#..#.#.
+            .###.####.
+            ..###.####
+            .##....##.
+            .#...####.
+            #.##.####.
+            ####..#...
+            .....##...
+
+            Tile 1427:
+            ###.##.#..
+            .#..#.##..
+            .#.##.#..#
+            #.#.#.##.#
+            ....#...##
+            ...##..##.
+            ...#.#####
+            .#.####.#.
+            ..#..###.#
+            ..##.#..#.
+
+            Tile 1489:
+            ##.#.#....
+            ..##...#..
+            .##..##...
+            ..#...#...
+            #####...#.
+            #..#.#.#.#
+            ...#.#.#..
+            ##.#...##.
+            ..##.##.##
+            ###.##.#..
+
+            Tile 2473:
+            #....####.
+            #..#.##...
+            #.##..#...
+            ######.#.#
+            .#...#.#.#
+            .#########
+            .###.#..#.
+            ########.#
+            ##...##.#.
+            ..###.#.#.
+
+            Tile 2971:
+            ..#.#....#
+            #...###...
+            #.#.###...
+            ##.##..#..
+            .#####..##
+            .#..####.#
+            #..#.#..#.
+            ..####.###
+            ..#.#.###.
+            ...#.#.#.#
+
+            Tile 2729:
+            ...#.#.#.#
+            ####.#....
+            ..#.#.....
+            ....#..#.#
+            .##..##.#.
+            .#.####...
+            ####.#.#..
+            ##.####...
+            ##..#.##..
+            #.##...##.
+
+            Tile 3079:
+            #.#.#####.
+            .#..######
+            ..#.......
+            ######....
+            ####.#..#.
+            .#...#.##.
+            #.#####.##
+            ..#.###...
+            ..#.......
+            ..#.###...
+        """.trimIndent()
+    )) {
+        println(part2())
+    }
+}