From cc8abea2c4954b09344a5b3989ddd66862c30321 Mon Sep 17 00:00:00 2001
From: Sven Weidauer <sven@5sw.de>
Date: Tue, 3 Dec 2024 18:55:52 +0100
Subject: [PATCH] Day 3.

---
 2024/src/main/kotlin/Utils.kt |  8 ++++++--
 2024/src/main/kotlin/day3.kt  | 25 ++++++++++++++++++++++++-
 2 files changed, 30 insertions(+), 3 deletions(-)

diff --git a/2024/src/main/kotlin/Utils.kt b/2024/src/main/kotlin/Utils.kt
index 8183282..232ead7 100644
--- a/2024/src/main/kotlin/Utils.kt
+++ b/2024/src/main/kotlin/Utils.kt
@@ -1,4 +1,8 @@
-fun readInput(name: String) = object {}.javaClass.getResourceAsStream(name)
-    ?.bufferedReader()
+fun readInput(name: String) = bufferedReader(name)
     ?.lineSequence()
     ?: error("Cannot read input")
+
+fun readInputString(name: String): String = bufferedReader(name)?.readText() ?: error("Cannot read input")
+
+private fun bufferedReader(name: String) = object {}.javaClass.getResourceAsStream(name)
+    ?.bufferedReader()
diff --git a/2024/src/main/kotlin/day3.kt b/2024/src/main/kotlin/day3.kt
index a104310..7b2af65 100644
--- a/2024/src/main/kotlin/day3.kt
+++ b/2024/src/main/kotlin/day3.kt
@@ -1,3 +1,26 @@
 fun main() {
-    
+    val input = readInputString("day3.txt")
+    val regexPart1 = "mul\\((\\d+),(\\d+)\\)".toRegex()
+
+    val part1 = regexPart1.findAll(input).fold(0) { acc, result ->
+        val (a, b) = result.destructured
+        acc + a.toInt() * b.toInt()
+    }
+
+    println("Part 1: $part1")
+
+    val regexPart2 = "do\\(\\)|don't\\(\\)|mul\\((\\d+),(\\d+)\\)".toRegex()
+    var enabled = true
+    var part2 = 0
+    for (command in regexPart2.findAll(input)) {
+        when (command.value) {
+            "do()" -> enabled = true
+            "don't()" -> enabled = false
+            else -> if (enabled) {
+                val (a, b) = command.destructured
+                part2 += a.toInt() * b.toInt()
+            }
+        }
+    }
+    println("Part 2: $part2")
 }
\ No newline at end of file