aoc2024

commit beb42f5f4e4b11f885a738876978b067607b8840
parent d6ae2c784752671804624e8259d52ed6e6208956
Author: Martin Ashby <martin@ashbysoft.com>
Date:   Tue,  3 Dec 2024 23:12:04 +0000

Day3 pt2

Diffstat:
A
day3_sample2.txt
 | 
2
++
M
src/main/scala/Day3.scala
 | 
27
+++++++++++++++++++++++++++
M
src/main/scala/Main.scala
 | 
4
++--

3 files changed, 31 insertions(+), 2 deletions(-)
diff --git a/day3_sample2.txt b/day3_sample2.txt
@@ -0,0 +1 @@
+xmul(2,4)&mul[3,7]!^don't()_mul(5,5)+mul(32,64](mul(11,8)undo()?mul(8,5))
+\ No newline at end of file
diff --git a/src/main/scala/Day3.scala b/src/main/scala/Day3.scala
@@ -3,6 +3,33 @@ def day3_pt1(input: Iterator[String]): Int =
   List.range(0, line.size)
     .flatMap(n => try_mul(line.substring(n)))
     .sum
+
+def day3_pt2(input: Iterator[String]): Int =
+    val line = input.next()
+    val (_, res) = List.range(0, line.size)
+        .foldLeft[(Boolean,Int)]((true, 0)) { (z: (Boolean, Int), n: Int) => 
+            val (enabled, sum) = z
+            val l1 = line.substring(n)
+            if enabled then
+                if try_dont(l1) then
+                    (false, sum)
+                else 
+                    (true, sum + try_mul(line.substring(n)).getOrElse(0))
+            else
+                if try_do(l1) then
+                    (true, sum)
+                else
+                    (false, sum)
+        }
+    res
+    
+
+def try_do(s: String): Boolean =
+    return s.startsWith("do()")
+
+def try_dont(s: String): Boolean =
+    return s.startsWith("don't()")
+
 def try_mul(s: String): Option[Int] =
     if s.startsWith("mul(") then
         val ix = s.indexOf(")")
diff --git a/src/main/scala/Main.scala b/src/main/scala/Main.scala
@@ -1,2 +1,2 @@
 @main def run(): Unit = 
-  println(day3_pt1(scala.io.Source.fromFile("day3.txt").getLines()))
-\ No newline at end of file
+  println(day3_pt2(scala.io.Source.fromFile("day3.txt").getLines()))
+\ No newline at end of file