Year 2019 Day 7

Author: maneatingape

README.md

@@ -74,3 +74,4 @@ Entries for the annual [Advent of Code](https://adventofcode.com/) challenge, wr
 | 4 | [Secure Container](https://adventofcode.com/2019/day/4) | [Source](src/main/scala/AdventOfCode2019/Day04.scala) |
 | 5 | [Sunny with a Chance of Asteroids](https://adventofcode.com/2019/day/5) | [Source](src/main/scala/AdventOfCode2019/Day05.scala) |
 | 6 | [Universal Orbit Map](https://adventofcode.com/2019/day/6) | [Source](src/main/scala/AdventOfCode2019/Day06.scala) |
+| 7 | [Amplification Circuit](https://adventofcode.com/2019/day/7) | [Source](src/main/scala/AdventOfCode2019/Day07.scala) |

src/main/resources/AdventOfCode2019/Day07.txt

@@ -0,0 +1 @@
+3,8,1001,8,10,8,105,1,0,0,21,46,59,84,93,102,183,264,345,426,99999,3,9,1002,9,4,9,1001,9,3,9,102,2,9,9,1001,9,5,9,102,3,9,9,4,9,99,3,9,1002,9,3,9,101,4,9,9,4,9,99,3,9,1002,9,4,9,1001,9,4,9,102,2,9,9,1001,9,2,9,1002,9,3,9,4,9,99,3,9,1001,9,5,9,4,9,99,3,9,1002,9,4,9,4,9,99,3,9,101,2,9,9,4,9,3,9,102,2,9,9,4,9,3,9,1001,9,1,9,4,9,3,9,1001,9,1,9,4,9,3,9,1002,9,2,9,4,9,3,9,101,1,9,9,4,9,3,9,1001,9,2,9,4,9,3,9,102,2,9,9,4,9,3,9,1001,9,2,9,4,9,3,9,1002,9,2,9,4,9,99,3,9,101,1,9,9,4,9,3,9,102,2,9,9,4,9,3,9,1001,9,2,9,4,9,3,9,101,2,9,9,4,9,3,9,101,2,9,9,4,9,3,9,101,2,9,9,4,9,3,9,1002,9,2,9,4,9,3,9,101,2,9,9,4,9,3,9,1001,9,1,9,4,9,3,9,101,1,9,9,4,9,99,3,9,1002,9,2,9,4,9,3,9,1002,9,2,9,4,9,3,9,101,1,9,9,4,9,3,9,1002,9,2,9,4,9,3,9,101,2,9,9,4,9,3,9,1001,9,2,9,4,9,3,9,101,2,9,9,4,9,3,9,101,1,9,9,4,9,3,9,1002,9,2,9,4,9,3,9,102,2,9,9,4,9,99,3,9,102,2,9,9,4,9,3,9,102,2,9,9,4,9,3,9,1001,9,1,9,4,9,3,9,1001,9,1,9,4,9,3,9,101,1,9,9,4,9,3,9,102,2,9,9,4,9,3,9,102,2,9,9,4,9,3,9,1002,9,2,9,4,9,3,9,102,2,9,9,4,9,3,9,1001,9,1,9,4,9,99,3,9,101,1,9,9,4,9,3,9,1002,9,2,9,4,9,3,9,102,2,9,9,4,9,3,9,1002,9,2,9,4,9,3,9,101,1,9,9,4,9,3,9,101,1,9,9,4,9,3,9,1001,9,2,9,4,9,3,9,101,2,9,9,4,9,3,9,101,1,9,9,4,9,3,9,101,1,9,9,4,9,99

src/main/scala/AdventOfCode2019/Day07.scala

@@ -0,0 +1,63 @@
+package AdventOfCode2019
+
+import scala.annotation.tailrec
+
+object Day07:
+  object IntCode:
+    val powers = Map(1 -> 100, 2 -> 1000)
+
+    sealed trait State
+    case object Initial extends State
+    case object Running extends State
+    case object Halted extends State
+    case class Output(value: Int) extends State
+
+    def apply(code: Seq[Int]): IntCode = IntCode(0, code, Seq(), Initial)
+  end IntCode
+
+  case class IntCode(ip: Int, code: Seq[Int], input: Seq[Int], result: IntCode.State):
+    import IntCode._
+
+    private def next: IntCode = code(ip) % 100 match
+      case 1 => IntCode(ip + 4, write(3, read(1) + read(2)), input, Running)                    // Add
+      case 2 => IntCode(ip + 4, write(3, read(1) * read(2)), input, Running)                    // Multiply
+      case 3 => IntCode(ip + 2, write(1, input.head), input.tail, Running)                      // Read
+      case 4 => IntCode(ip + 2, code, input, Output(read(1)))                                   // Write
+      case 5 => IntCode(if read(1) != 0 then read(2) else ip + 3, code, input, Running)         // Jump if true
+      case 6 => IntCode(if read(1) == 0 then read(2) else ip + 3, code, input, Running)         // Jump if false
+      case 7 => IntCode(ip + 4, write(3, if read(1) < read(2) then 1 else 0), input, Running)   // Less than
+      case 8 => IntCode(ip + 4, write(3, if read(1) == read(2) then 1 else 0), input, Running)  // Equals
+      case 99 => IntCode(ip, code, input, Halted)                                               // Halt
+
+    private def read(offset: Int): Int = (code(ip) / powers(offset)) % 10 match
+      case 0 => code(code(ip + offset))
+      case 1 => code(ip + offset)
+
+    private def write(offset: Int, value: Int): Seq[Int] = code.updated(code(ip + offset), value)
+
+    def withInput(next: Int*): IntCode = copy(input = input.appendedAll(next))
+
+    def nextOutput: IntCode = Iterator.iterate(next)(_.next).dropWhile(_.result == Running).next()
+
+    def allOutput: Seq[Int] =
+      val output = Iterator.iterate(this)(_.nextOutput).takeWhile(_.result != Halted)
+      output.toSeq.map(_.result).collect { case Output(value) => value }
+  end IntCode
+
+  def part1(code: Seq[Int]): Int = (0 to 4).permutations.map(_.foldLeft(0)((total, next) => IntCode(code).withInput(next, total).allOutput.last)).max
+
+  def part2(code: Seq[Int]): Int =
+    @tailrec
+    def helper(previousOutput: Int)(amps: Seq[IntCode]): Int =
+      val nextAmp = amps.head.withInput(previousOutput).nextOutput
+      nextAmp.result match
+        case IntCode.Output(nextOutput) => helper(nextOutput)(amps.tail.appended(nextAmp))
+        case _ => previousOutput
+
+    (5 to 9).map(phase => IntCode(code).withInput(phase)).permutations.map(helper(0)).max
+  end part2
+
+  def main(args: Array[String]): Unit =
+    val data = io.Source.fromResource("AdventOfCode2019/Day07.txt").mkString.trim.split(",").map(_.toInt).toSeq
+    println(part1(data))
+    println(part2(data))

src/test/scala/AdventOfCode2019/Day07Suite.scala

@@ -0,0 +1,16 @@
+package AdventOfCode2019
+
+import org.scalatest.funsuite.AnyFunSuite
+
+class Day07Suite extends AnyFunSuite:
+  val sample1 = Seq(3,31,3,32,1002,32,10,32,1001,31,-2,31,1007,31,0,33,1002,33,7,33,1,33,31,31,1,32,31,31,4,31,99,0,0,0)
+
+  test("Part 1 should handle sample input correctly") {
+    assert(Day07.part1(sample1) == 65210)
+  }
+
+  val sample2 = Seq(3,26,1001,26,-4,26,3,27,1002,27,2,27,1,27,26,27,4,27,1001,28,-1,28,1005,28,6,99,0,0,5)
+
+  test("Part 2 should handle sample input correctly") {
+    assert(Day07.part2(sample2) == 139629729)
+  }