Day22

days/src/main/kotlin/Day21.kt

@@ -25,7 +25,7 @@ class Day21(@Lines val input: Input<List<String>>) {
         val occurrences = Bags.mutable.empty<String>()
         foods.forEach { (ingredients) -> occurrences.addAll(ingredients) }
         return allIngredients.filter { !dangerousIngredients.containsValue(it) }
-            .map { occurrences.count { it == it } }
+            .map { ingredient -> occurrences.count { it == ingredient } }
             .sum()
     }
 

days/src/main/kotlin/Day22.kt

@@ -0,0 +1,81 @@
+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
+
+data class PlayedGame(val a: List<Int>, val b: List<Int>)
+
+@Day(22)
+class Day22(@Groups val input: Input<List<List<String>>>) {
+    private val one = input.value[0].drop(1).map { it.toInt() }
+    private val two = input.value[1].drop(1).map { it.toInt() }
+
+    fun part1(): Long {
+        val oneDeque = ArrayDeque<Int>().apply { one.forEach { addFirst(it) } }
+        val twoDeque = ArrayDeque<Int>().apply { two.forEach { addFirst(it) } }
+
+        while (oneDeque.isNotEmpty() && twoDeque.isNotEmpty()) {
+            val a = oneDeque.removeLast()
+            val b = twoDeque.removeLast()
+
+            if (a > b) {
+                oneDeque.addFirst(a)
+                oneDeque.addFirst(b)
+            } else {
+                twoDeque.addFirst(b)
+                twoDeque.addFirst(a)
+            }
+        }
+
+        val deque = if (oneDeque.isEmpty()) twoDeque else oneDeque
+        return deque.mapIndexed { index, value -> (index + 1).toLong() * value.toLong() }.sum()
+    }
+
+    fun part2(): Long {
+        val oneDeque = ArrayDeque<Int>().apply { one.forEach { addFirst(it) } }
+        val twoDeque = ArrayDeque<Int>().apply { two.forEach { addFirst(it) } }
+
+        val winner = playGame(oneDeque, twoDeque)
+        val deque = if (winner == 1) oneDeque else twoDeque
+        return deque.mapIndexed { index, value -> (index + 1).toLong() * value.toLong() }.sum()
+    }
+
+    private fun playGame(one: ArrayDeque<Int>, two: ArrayDeque<Int>): Int {
+        val playedGames = mutableSetOf<PlayedGame>()
+
+        while (one.isNotEmpty() && two.isNotEmpty()) {
+            if (!playedGames.add(PlayedGame(one.toList(), two.toList()))) return 1
+
+            val a = one.removeLast()
+            val b = two.removeLast()
+
+            val winner = when {
+                one.size >= a && two.size >= b -> playGame(
+                    ArrayDeque(one.drop(one.size - a)),
+                    ArrayDeque(two.drop(two.size - b))
+                )
+                a > b -> 1
+                else -> 2
+            }
+
+            if (winner == 1) {
+                one.addFirst(a)
+                one.addFirst(b)
+            } else {
+                two.addFirst(b)
+                two.addFirst(a)
+            }
+
+        }
+
+        return if (one.isEmpty()) 2 else 1
+    }
+}
+
+fun main() = with(createDay<Day22>()) {
+    println(part1())
+    println(part2())
+}
+

days/src/main/resources/day22.txt

@@ -0,0 +1,53 @@
+Player 1:
+21
+48
+44
+31
+29
+5
+23
+11
+12
+27
+49
+22
+18
+7
+15
+20
+2
+45
+14
+17
+40
+35
+6
+24
+41
+
+Player 2:
+47
+1
+10
+16
+28
+37
+8
+26
+46
+25
+3
+9
+34
+50
+32
+36
+43
+4
+42
+33
+19
+13
+38
+39
+30