Prepare for other years

2020-12-30 18:01:52 +01:00
parent 522618d106
commit 4a90257257
81 changed files with 277 additions and 253 deletions
@@ -0,0 +1,66 @@
+package be.vandewalleh.aoc.days
+
+import be.vandewalleh.aoc.utils.input.Day
+import be.vandewalleh.aoc.utils.input.Input
+import be.vandewalleh.aoc.utils.input.Lines
+import org.eclipse.collections.api.bag.Bag
+import org.eclipse.collections.api.bag.MutableBag
+import org.eclipse.collections.api.factory.Bags
+
+@Day(24)
+class Day24(@Lines val input: Input<List<String>>) {
+
+    private data class HexPoint(val x: Int, val y: Int, val z: Int) {
+        fun translate(other: HexPoint) = HexPoint(this.x + other.x, this.y + other.y, this.z + other.z)
+    }
+
+    private enum class Direction(vararg coordinates: Int) {
+        E(1, -1, 0),
+        SE(0, -1, 1),
+        SW(-1, 0, 1),
+        W(-1, 1, 0),
+        NW(0, 1, -1),
+        NE(1, 0, -1);
+
+        val coordinates = HexPoint(coordinates[0], coordinates[1], coordinates[2])
+    }
+
+    private fun parseTile(line: String) = "e|se|sw|w|nw|ne".toRegex()
+        .findAll(line)
+        .flatMap { it.groupValues }
+        .map { Direction.valueOf(it.toUpperCase()) }
+        .toList()
+
+    private val tiles = input.value.map { parseTile(it) }.map {
+        it.map { it.coordinates }.reduce { acc, ints -> acc.translate(ints) }
+    }
+
+    fun part1() = Bags.immutable.ofAll(tiles).selectBlacks().size()
+
+    private fun Bag<HexPoint>.selectBlacks() = selectByOccurrences { it % 2 == 1 }
+
+    private fun HexPoint.adjacents() = Direction.values().map { this.translate(it.coordinates) }
+
+    // black -> odd
+    // white -> even || not in bag -> !in black
+    private fun day(bag: MutableBag<HexPoint>) {
+        val blacks = bag.selectBlacks().toSet()
+
+        val all = (bag + bag.flatMap { it.adjacents() }).toSet()
+
+        for (tile in all) {
+            val adjacents = tile.adjacents()
+            val adjacentBlacks = adjacents.count { it in blacks }
+            val isBlack = tile in blacks
+
+            if (isBlack && (adjacentBlacks == 0 || adjacentBlacks > 2)) bag.setOccurrences(tile, 2)
+            else if (!isBlack && adjacentBlacks == 2) bag.setOccurrences(tile, 1)
+        }
+    }
+
+    fun part2(): Int {
+        val bag = Bags.mutable.ofAll(tiles)
+        repeat(100) { day(bag) }
+        return bag.selectBlacks().size()
+    }
+}