2015 day 12 part 2

Author: sanderploegsma

2015/kotlin/build.gradle.kts

@@ -16,8 +16,9 @@ repositories {
 }
 
 dependencies {
-    testImplementation(kotlin("test"))
+    implementation("org.jetbrains.kotlinx", "kotlinx-serialization-json", "1.6.2")
 
+    testImplementation(kotlin("test"))
     testImplementation("org.junit.jupiter", "junit-jupiter-params", junitVersion)
     testImplementation("org.amshove.kluent", "kluent", "1.68")
 }

2015/kotlin/src/main/kotlin/nl/sanderp/aoc/aoc2015/day12/Day12.kt

@@ -1,10 +1,19 @@
 package nl.sanderp.aoc.aoc2015.day12
 
+import kotlinx.serialization.json.*
 import nl.sanderp.aoc.common.readResource
 
-fun findNumbers(input: String) = Regex("""[0-9\-]+""").findAll(input).map { it.value.toInt() }
+fun sumNumbers(element: JsonElement) = sumNumbers(element) { false }
+
+fun sumNumbers(element: JsonElement, ignoreObject: (JsonObject) -> Boolean): Int = when {
+    element is JsonPrimitive -> element.intOrNull ?: 0
+    element is JsonArray -> element.sumOf { sumNumbers(it, ignoreObject) }
+    element is JsonObject && !ignoreObject(element) -> element.values.sumOf { sumNumbers(it, ignoreObject) }
+    else -> 0
+}
 
 fun main() {
-    val input = readResource("Day12.txt")
-    println("Part one: ${findNumbers(input).sum()}")
+    val input = Json.decodeFromString<JsonElement>(readResource("Day12.txt"))
+    println("Part one: ${sumNumbers(input)}")
+    println("Part two: ${sumNumbers(input) { it.containsValue(JsonPrimitive("red")) }}")
 }