From e72f71c1bf78b8c89be14add9e4407593315e47c Mon Sep 17 00:00:00 2001
From: Hubert Van De Walle <hubv@protonmail.com>
Date: Thu, 24 Dec 2020 16:11:12 +0100
Subject: [PATCH] Use custom class for faster hashcode

---
 days/src/main/kotlin/Day24.kt | 26 +++++++++-----------------
 1 file changed, 9 insertions(+), 17 deletions(-)

diff --git a/days/src/main/kotlin/Day24.kt b/days/src/main/kotlin/Day24.kt
index e90aa48..fa3d294 100644
--- a/days/src/main/kotlin/Day24.kt
+++ b/days/src/main/kotlin/Day24.kt
@@ -11,6 +11,10 @@ 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),
@@ -19,7 +23,7 @@ class Day24(@Lines val input: Input<List<String>>) {
         NW(0, 1, -1),
         NE(1, 0, -1);
 
-        val coordinates = coordinates
+        val coordinates = HexPoint(coordinates[0], coordinates[1], coordinates[2])
     }
 
     private fun parseTile(line: String) = "e|se|sw|w|nw|ne".toRegex()
@@ -29,30 +33,18 @@ class Day24(@Lines val input: Input<List<String>>) {
         .toList()
 
     private val tiles = input.value.map { parseTile(it) }.map {
-        it.map { it.coordinates }
-            .reduce { acc, ints -> intArrayOf(acc[0] + ints[0], acc[1] + ints[1], acc[2] + ints[2]) }
-            .toList()
+        it.map { it.coordinates }.reduce { acc, ints -> acc.translate(ints) }
     }
 
     fun part1() = Bags.immutable.ofAll(tiles).selectBlacks().size()
 
-    private fun Bag<List<Int>>.selectBlacks() = selectByOccurrences { it % 2 == 1 }
+    private fun Bag<HexPoint>.selectBlacks() = selectByOccurrences { it % 2 == 1 }
 
-    private fun List<Int>.adjacents(): List<List<Int>> {
-        val (x, y, z) = this
-        return listOf(
-            listOf(x + 1, y - 1, z),
-            listOf(x, y - 1, z + 1),
-            listOf(x - 1, y, z + 1),
-            listOf(x - 1, y + 1, z),
-            listOf(x, y + 1, z - 1),
-            listOf(x + 1, y, z - 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<List<Int>>) {
+    private fun day(bag: MutableBag<HexPoint>) {
         val blacks = bag.selectBlacks().toSet()
 
         val all = (bag + bag.flatMap { it.adjacents() }).toSet()