Day 5

aoc/src/Day5.scala

@@ -0,0 +1,49 @@
+import scala.io.Source
+import scala.collection.mutable.Stack
+
+object Day5 extends App:
+
+  val input = Source
+    .fromURL(getClass.getResource("day5Input.txt"))
+    .mkString
+    .split('\n')
+    .toList
+
+  val crates = input
+    .takeWhile(_ != "")
+    .dropRight(1)
+    .map(_.grouped(4).toList)
+    .transpose
+    .map(_.flatMap(_.find(_.isLetter)))
+    .toArray
+
+  val moves = input
+    .dropWhile(_ != "")
+    .tail
+    .map(_.split(" ").flatMap(_.toIntOption))
+    .map { case Array(count, from, to) => (count, from - 1, to - 1) }
+
+  val part1 = moves
+    .foldLeft(crates) { case (crates, (count, from, to)) =>
+      val movedCrates = crates(from).take(count)
+      crates
+        .updated(from, crates(from).drop(count))
+        .updated(to, crates(to).prependedAll(movedCrates.reverse))
+    }.toList
+    .map(_.head)
+    .mkString
+
+  println(s"Part 1: $part1")
+
+  val part2 = moves
+    .foldLeft(crates) { case (crates, (count, from, to)) =>
+      val movedCrates = crates(from).take(count)
+      crates
+        .updated(from, crates(from).drop(count))
+        .updated(to, crates(to).prependedAll(movedCrates))
+    }.toList
+    .map(_.head)
+    .mkString
+
+  println(s"Part 2: $part2")
+end Day5