Prepare for other years

2020-12-30 18:01:52 +01:00
parent 522618d106
commit 4a90257257
81 changed files with 277 additions and 253 deletions
@@ -0,0 +1,57 @@
+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 java.util.*
+import kotlin.collections.ArrayList
+
+@Day(19)
+class Day19(@Groups val input: Input<List<List<String>>>) {
+    private val rules = input.value[0]
+    private val messages = input.value[1]
+
+    sealed class Rule {
+        data class CharRule(val value: Char) : Rule()
+        data class OrRule(val a: List<Int>, val b: List<Int>?) : Rule() {
+            val all get() = listOfNotNull(a, b)
+        }
+    }
+
+    private fun parseRules(): Map<Int, Rule> {
+        val parsedRules = mutableMapOf<Int, Rule>()
+        rules.forEach {
+            val parts = it.split(":", limit = 2)
+            val index = parts[0].toInt()
+            val rule = if ("\"" !in parts[1]) {
+                val p = parts[1].split('|', limit = 2).map { it.trim().split(" ").mapTo(ArrayList(2)) { it.toInt() } }
+                Rule.OrRule(p[0], if (p.size == 2) p[1] else null)
+            } else {
+                Rule.CharRule(parts[1].trim().replace("\"", "")[0])
+            }
+            parsedRules[index] = rule
+        }
+        return parsedRules
+    }
+
+    private fun matches(input: String, queue: ArrayDeque<Int>, rules: Map<Int, Rule>): Boolean =
+        if (queue.isEmpty()) input.isEmpty()
+        else if (input.isEmpty()) queue.isEmpty()
+        else when (val rule = rules[queue.pop()]!!) {
+            is Rule.CharRule -> input[0] == rule.value && matches(input.drop(1), queue, rules)
+            is Rule.OrRule -> rule.all.any { matches(input, queue.clone().apply { it.asReversed().forEach { addFirst(it) } }, rules) }
+        }
+
+    fun part1(): Int {
+        val rules = parseRules()
+        return messages.count { matches(it, ArrayDeque<Int>().apply { add(0) }, rules) }
+    }
+
+    fun part2(): Int {
+        val rules = parseRules().toMutableMap()
+        rules[8] = Rule.OrRule(listOf(42), listOf(42, 8))
+        rules[11] = Rule.OrRule(listOf(42, 31), listOf(42, 11, 31))
+        return messages.count { matches(it, ArrayDeque<Int>().apply { add(0) }, rules) }
+    }
+
+}