From 34259208d562960601c91744983bf662820648f3 Mon Sep 17 00:00:00 2001
From: Hubert Van De Walle <hubv@protonmail.com>
Date: Thu, 10 Dec 2020 08:47:44 +0100
Subject: [PATCH] Day10

---
 days/src/main/kotlin/Day10.kt     | 50 +++++++++++++++++
 days/src/main/resources/day10.txt | 93 +++++++++++++++++++++++++++++++
 2 files changed, 143 insertions(+)
 create mode 100644 days/src/main/kotlin/Day10.kt
 create mode 100644 days/src/main/resources/day10.txt

diff --git a/days/src/main/kotlin/Day10.kt b/days/src/main/kotlin/Day10.kt
new file mode 100644
index 0000000..0208091
--- /dev/null
+++ b/days/src/main/kotlin/Day10.kt
@@ -0,0 +1,50 @@
+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 be.vandewalleh.aoc.utils.input.createDay
+import org.eclipse.collections.api.list.primitive.MutableIntList
+import org.eclipse.collections.impl.factory.primitive.IntLists
+import org.eclipse.collections.impl.factory.primitive.IntLongMaps
+
+@Day(10)
+class Day10(@Lines val input: Input<IntArray>) {
+
+    fun part1(): Int {
+        val sorted = IntLists.mutable.of(0, *input.value).apply {
+            sortThis()
+            add(last + 3)
+        }.toArray().toList()
+
+        var ones = 0
+        var threes = 0
+
+        sorted.zipWithNext().forEach { (a, b) ->
+            if (a + 1 == b) ones++
+            else if (a + 3 == b) threes++
+        }
+
+        return ones * threes
+    }
+
+    fun part2(): Long {
+        val sorted: MutableIntList = IntLists.mutable.of(*input.value).apply { sortThis() }
+
+        val map = IntLongMaps.mutable.empty().apply {
+            put(0, 1L)
+        }
+
+        sorted.forEach { i ->
+            map.put(i, map.get(i - 1) + map.get(i - 2) + map.get(i - 3))
+        }
+
+        return map.get(sorted.last)
+    }
+
+}
+
+fun main() = with(createDay<Day10>()) {
+    println(part1())
+    println(part2())
+}
diff --git a/days/src/main/resources/day10.txt b/days/src/main/resources/day10.txt
new file mode 100644
index 0000000..e4c0d57
--- /dev/null
+++ b/days/src/main/resources/day10.txt
@@ -0,0 +1,93 @@
+47
+99
+115
+65
+10
+55
+19
+73
+80
+100
+71
+110
+64
+135
+49
+3
+1
+98
+132
+2
+38
+118
+66
+116
+104
+87
+79
+114
+40
+37
+44
+97
+4
+140
+60
+86
+56
+133
+7
+146
+85
+111
+134
+53
+121
+77
+117
+21
+12
+81
+145
+129
+107
+93
+22
+48
+11
+54
+92
+78
+67
+20
+138
+125
+57
+96
+26
+147
+124
+34
+74
+143
+13
+28
+126
+50
+29
+70
+39
+63
+41
+91
+32
+84
+144
+27
+139
+33
+88
+72
+23
+103
+16