AoC 2024 Day 19 Part 2

GeistInDerSH · Dec 20, 2024 · 53bafea · 53bafea
1 parent 32641c8
commit 53bafea
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Showing 2 changed files with 22 additions and 17 deletions.
diff --git a/src/main/kotlin/com/geistindersh/aoc/year2024/Day19.kt b/src/main/kotlin/com/geistindersh/aoc/year2024/Day19.kt
@@ -8,23 +8,20 @@ import java.util.PriorityQueue
 class Day19(
     private val patterns: Set<String>,
     private val designs: List<String>,
-    private val debug: Boolean = false,
 ) {
-    constructor(dataFile: DataFile, debug: Boolean = false) : this(fileToString(2024, 19, dataFile), debug)
-    constructor(input: String, debug: Boolean = false) : this(
+    constructor(dataFile: DataFile) : this(fileToString(2024, 19, dataFile))
+    constructor(input: String) : this(
         input
             .substringBefore("\n")
             .split(',')
             .map { it.trim() }
             .sortedByDescending { it.length }
             .toSet(),
         input.substringAfter("\n").split("\n").drop(1),
-        debug,
     )
 
     private fun String.isValid(): Boolean {
         if (this.isEmpty()) return true
-        if (debug) println(this)
 
         val queue = PriorityQueue<String>(compareBy { it.length }).apply { add(this@isValid) }
         val seen = mutableSetOf<String>()
@@ -33,7 +30,6 @@ class Day19(
             if (head.isBlank()) return true
             if (!seen.add(head)) continue
             if (head in patterns) return true
-            if (debug) println(head)
 
             for (pattern in patterns) {
                 if (!head.startsWith(pattern)) continue
@@ -44,18 +40,28 @@ class Day19(
         return false
     }
 
-    init {
-        println()
-    }
+    private fun String.validComboCount(): Long {
+        val queue = PriorityQueue<String>(compareByDescending { it.length }).apply { add(this@validComboCount) }
+        val memory = mutableMapOf<String, Long>(this to 1L)
 
-    fun part1() =
-        designs.count {
-            val v = it.isValid()
-            println("$it: $v")
-            v
+        while (queue.isNotEmpty()) {
+            val head = queue.poll()
+
+            for (pattern in patterns) {
+                if (!head.startsWith(pattern)) continue
+                val substring = head.substringAfter(pattern)
+                if (substring !in memory) {
+                    queue.add(substring)
+                }
+                memory[substring] = memory.getOrDefault(substring, 0L) + memory[head]!!
+            }
         }
+        return memory.getOrDefault("", 0L)
+    }
+
+    fun part1() = designs.count { it.isValid() }
 
-    fun part2() = 0
+    fun part2() = designs.filter { it.isValid() }.sumOf { it.validComboCount() }
 }
 
 fun day19() {

diff --git a/src/test/kotlin/com/geistindersh/aoc/year2024/Day19Test.kt b/src/test/kotlin/com/geistindersh/aoc/year2024/Day19Test.kt
@@ -12,7 +12,6 @@ class Day19Test {
 
     @Test
     fun part2() {
-        assertEquals(-1, Day19(DataFile.Example).part2())
-        assertEquals(-1, Day19(DataFile.Part1).part2())
+        assertEquals(16, Day19(DataFile.Example).part2())
     }
 }