Day 10

aoc/src/Day10.scala

@@ -0,0 +1,49 @@
+import scala.io.Source
+
+object Day10 extends App:
+
+  val input = Source
+    .fromURL(getClass.getResource("day10Input.txt"))
+    .mkString
+    .split('\n')
+    .toList
+    .map(_.split(" ")).map {
+      case Array(inst, value) => (inst, value.toInt)
+      case Array(inst)        => (inst, 0)
+    }
+    .flatMap {
+      case inst @ ("noop", _) => List(inst)
+      case inst @ ("addx", _) => List(("noop", 0), inst)
+    }
+
+  val execution = input.scanLeft((1, 1)) {
+    case ((register, cycle), ("noop", _))     => (register, cycle + 1)
+    case ((register, cycle), ("addx", value)) => (register + value, cycle + 1)
+    case ((register, cycle), _)               => (register, cycle + 1)
+  }
+
+  val interestingSignals =
+    (20 to execution.last._2).filter(cycle => cycle == 20 || (cycle + 20) % 40 == 0)
+
+  val part1 = execution
+    .filter(state => interestingSignals.contains(state._2))
+    .map(_._1)
+    .zip(interestingSignals)
+    .map(_ * _)
+    .sum
+  println(s"Part 1: $part1")
+
+  def renderRow(rowExecution: List[(Int, Int)]): String =
+    rowExecution.foldLeft("") { case (line, (register, cycle)) =>
+      val spritePosition = register - 1 to register + 1
+      if spritePosition.contains((cycle - 1) % 40) then line + "#"
+      else line + "."
+    }
+
+  val part2 = execution
+    .grouped(40)
+    .map(renderRow)
+    .mkString("\n")
+  println(s"Part 2:")
+  println(part2)
+end Day10