Day21

2020-12-21 08:20:42 +01:00
parent 6689a739bc
commit 9490164d09
2 changed files with 113 additions and 0 deletions
@@ -0,0 +1,64 @@
+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.factory.Bags
+import org.eclipse.collections.api.multimap.set.MutableSetMultimap
+import org.eclipse.collections.impl.factory.Multimaps
+
+@Day(21)
+class Day21(@Lines val input: Input<List<String>>) {
+    private val foods = input.value.map { line ->
+        val parOpen = line.indexOf('(')
+        val ingredients = line.substring(0 until parOpen - 1).split(" ")
+        val allergens = line.substring(parOpen + 1 until line.length - 1).removePrefix("contains ").split(", ")
+        ingredients to allergens
+    }
+
+    private val allIngredients = foods.flatMap { it.first }.toSet()
+    private val allAllergens = foods.flatMap { it.second }.toSet()
+    private val dangerousIngredients = dangerousIngredients()
+
+    fun part1(): Int {
+        val occurrences = Bags.mutable.empty<String>()
+        foods.forEach { (ingredients) -> occurrences.addAll(ingredients) }
+        return allIngredients.filter { !dangerousIngredients.containsValue(it) }
+            .map { occurrences.count { it == it } }
+            .sum()
+    }
+
+    fun part2(): String {
+        while (!dangerousIngredients.multiValuesView().all { it.size() == 1 }) {
+            dangerousIngredients.multiValuesView()
+                .filter { it.size() == 1 }
+                .map { it.first() }
+                .forEach { removeMe ->
+                    dangerousIngredients.keyMultiValuePairsView()
+                        .filter { it.two.size() != 1 && it.two.contains(removeMe) }
+                        .forEach { dangerousIngredients.remove(it.one, removeMe) }
+                }
+        }
+        return dangerousIngredients.keySet().sorted().joinToString(",") { dangerousIngredients.get(it).first() }
+    }
+
+    private fun dangerousIngredients(): MutableSetMultimap<String, String> {
+        val map = Multimaps.mutable.set.empty<String, String>()
+        allAllergens.forEach { map.putAll(it, allIngredients) }
+
+        foods.forEach { (ingredients, allergens) ->
+            allergens.forEach { allergen ->
+                allIngredients.forEach {
+                    if (!ingredients.contains(it)) map.remove(allergen, it)
+                }
+            }
+        }
+        return map
+    }
+}
+
+fun main() = with(createDay<Day21>()) {
+    println(part1())
+    println(part2())
+}