From 3a8a2d79a9c488cb36c24c59396f6d89e964ee45 Mon Sep 17 00:00:00 2001
From: chrisly42 <chrisly@platon42.de>
Date: Sat, 16 Dec 2023 13:19:03 +0100
Subject: [PATCH] Minor update to Day 15 because I should have used a linked
 hashmap in the first place, if I had only read the instructions clearly
 enough.

---
 src/aoc2023/Day15.kt | 21 +++++++--------------
 1 file changed, 7 insertions(+), 14 deletions(-)

diff --git a/src/aoc2023/Day15.kt b/src/aoc2023/Day15.kt
index cf5e011..0fe9fce 100644
--- a/src/aoc2023/Day15.kt
+++ b/src/aoc2023/Day15.kt
@@ -73,27 +73,20 @@ rn=1,cm-,qp=3,cm=2,qp-,pc=4,ot=9,ab=5,pc-,pc=6,ot=7
     }
 
     fun part2(input: List<String>): Int {
-        val boxes = Array<MutableList<String>>(256) { ArrayList() }
-        println(hash("cm"))
+        val boxes = Array<MutableMap<String, Int>>(256) { LinkedHashMap() }
         input.first().split(",").forEach { it ->
             if (it.contains('=')) {
                 val (label, value) = it.split("=")
-                val hash = hash(label)
-                if (boxes[hash].none { it.startsWith("$label ") }) {
-                    boxes[hash].add("$label $value")
-                } else {
-                    boxes[hash] = boxes[hash].map { content -> if (content.startsWith("$label ")) "$label $value" else content }.toMutableList()
-                }
+                boxes[hash(label)][label] = value.toInt()
             } else {
                 val label = it.removeSuffix("-")
-                val hash = hash(label)
-                boxes[hash] = boxes[hash].filterNot { it.startsWith("$label ") }.toMutableList()
+                boxes[hash(label)].remove(label)
             }
         }
-        val vals = boxes.mapIndexed { boxno, contents ->
-            contents.mapIndexed { index, strings -> (boxno + 1) * strings.split(" ")[1].toInt() * (index + 1) }.sum()
-        }
-        return vals.sum()
+        return boxes.mapIndexed { boxno, contents ->
+            contents.map { entry -> entry.value }
+                .mapIndexed { index, value -> (boxno + 1) * value * (index + 1) }.sum()
+        }.sum()
     }
 
     // test if implementation meets criteria from the description, like: