diff --git a/day1/part1.scala b/2018/day1/part1.scala
similarity index 100%
rename from day1/part1.scala
rename to 2018/day1/part1.scala
diff --git a/day1/part2.scala b/2018/day1/part2.scala
similarity index 100%
rename from day1/part2.scala
rename to 2018/day1/part2.scala
diff --git a/day10/bothparts.scala b/2018/day10/bothparts.scala
similarity index 100%
rename from day10/bothparts.scala
rename to 2018/day10/bothparts.scala
diff --git a/day11/part1.scala b/2018/day11/part1.scala
similarity index 100%
rename from day11/part1.scala
rename to 2018/day11/part1.scala
diff --git a/day11/part2.scala b/2018/day11/part2.scala
similarity index 100%
rename from day11/part2.scala
rename to 2018/day11/part2.scala
diff --git a/day12/part1.scala b/2018/day12/part1.scala
similarity index 100%
rename from day12/part1.scala
rename to 2018/day12/part1.scala
diff --git a/day12/part2.scala b/2018/day12/part2.scala
similarity index 100%
rename from day12/part2.scala
rename to 2018/day12/part2.scala
diff --git a/day13/part1.scala b/2018/day13/part1.scala
similarity index 100%
rename from day13/part1.scala
rename to 2018/day13/part1.scala
diff --git a/day14/part1.scala b/2018/day14/part1.scala
similarity index 100%
rename from day14/part1.scala
rename to 2018/day14/part1.scala
diff --git a/day15/part1.scala b/2018/day15/part1.scala
similarity index 100%
rename from day15/part1.scala
rename to 2018/day15/part1.scala
diff --git a/day15/part2.scala b/2018/day15/part2.scala
similarity index 100%
rename from day15/part2.scala
rename to 2018/day15/part2.scala
diff --git a/day16/part1.scala b/2018/day16/part1.scala
similarity index 100%
rename from day16/part1.scala
rename to 2018/day16/part1.scala
diff --git a/day16/part2.scala b/2018/day16/part2.scala
similarity index 100%
rename from day16/part2.scala
rename to 2018/day16/part2.scala
diff --git a/2018/day18/part1.scala b/2018/day18/part1.scala
new file mode 100644
index 0000000..1dd39c6
--- /dev/null
+++ b/2018/day18/part1.scala
@@ -0,0 +1,53 @@
+import scala.io.StdIn.readLine
+
+val OPEN = '.'
+val TREE = '|'
+val LMBR = '#'
+
+case class Pos(x: Int, y: Int) {
+  lazy val adjacent = List(
+    Pos(x - 1, y - 1),
+    Pos(x - 1, y),
+    Pos(x - 1, y + 1),
+    Pos(x, y - 1),
+    Pos(x, y + 1),
+    Pos(x + 1, y - 1),
+    Pos(x + 1, y),
+    Pos(x + 1, y + 1)
+  ).filter { case Pos(xx, yy) => xx >= 0 && xx < 50 && yy >= 0 && yy < 50 }
+
+  def adjacentChars(forest: Map[Pos, Char]): List[Char] = adjacent.map(forest)
+}
+
+val forest = Iterator.continually(readLine)
+  .takeWhile(_ != null)
+  .map(_.zipWithIndex)
+  .zipWithIndex
+  .flatMap { case (line, y) =>
+    line.map { case (char, x) => Pos(x, y) -> char }
+  }.toMap
+
+val forestEvolution = Iterator.from(1).scanLeft((0, forest)) {
+  case ((_, forest), turn) => (turn, forest.map {
+    case (p, OPEN) if p.adjacentChars(forest).count(_ == TREE) >= 3 => p -> TREE
+    case (p, OPEN) => p -> OPEN
+    case (p, TREE) if p.adjacentChars(forest).count(_ == LMBR) >= 3 => p -> LMBR
+    case (p, TREE) => p -> TREE
+    case (p, LMBR) if p.adjacentChars(forest).count(_ == LMBR) >= 1 && p.adjacentChars(forest).count(_ == TREE) >= 1 => p -> LMBR
+    case (p, LMBR) => p -> OPEN
+  })
+}
+
+def forestToString(forest: Map[Pos, Char]): String =
+  (0 to 49).map(y => (0 to 49).map(x => forest(Pos(x, y))).mkString("")).mkString("\n")
+
+val turns = forestEvolution
+  .take(11)
+  .toList
+  .foreach { case (turn, map) =>
+    println(s"Turn $turn")
+    val charCounts = map.groupBy(_._2).mapValues(_.size)
+    charCounts.foreach { case (c, cnt) => println(s"$c count: $cnt") }
+    println(s"Score: ${charCounts(TREE) * charCounts(LMBR)}")
+    println(forestToString(map))
+  }
diff --git a/2018/day19/part1.scala b/2018/day19/part1.scala
new file mode 100644
index 0000000..96e0bd1
--- /dev/null
+++ b/2018/day19/part1.scala
@@ -0,0 +1,68 @@
+import scala.io.StdIn.readLine
+
+def ifb(A: Int, B: Int, f: (Int, Int) => Boolean): Int = if (f(A, B)) {
+  1
+} else {
+  0
+}
+
+val OP_CODES: Map[String, ((Int, Int, Int, Registers) => Registers)] = Map(
+  "addr" -> ((A: Int, B: Int, C: Int, regs: List[Int]) => regs.patch(C, List(regs(A) + regs(B)), 1)),
+  "addi" -> ((A: Int, B: Int, C: Int, regs: List[Int]) => regs.patch(C, List(regs(A) + B), 1)),
+
+  "mulr" -> ((A: Int, B: Int, C: Int, regs: List[Int]) => regs.patch(C, List(regs(A) * regs(B)), 1)),
+  "muli" -> ((A: Int, B: Int, C: Int, regs: List[Int]) => regs.patch(C, List(regs(A) * B), 1)),
+
+  "banr" -> ((A: Int, B: Int, C: Int, regs: List[Int]) => regs.patch(C, List(regs(A) & regs(B)), 1)),
+  "bani" -> ((A: Int, B: Int, C: Int, regs: List[Int]) => regs.patch(C, List(regs(A) & B), 1)),
+
+  "borr" -> ((A: Int, B: Int, C: Int, regs: List[Int]) => regs.patch(C, List(regs(A) | regs(B)), 1)),
+  "bori" -> ((A: Int, B: Int, C: Int, regs: List[Int]) => regs.patch(C, List(regs(A) | B), 1)),
+
+  "setr" -> ((A: Int, B: Int, C: Int, regs: List[Int]) => regs.patch(C, List(regs(A)), 1)),
+  "seti" -> ((A: Int, B: Int, C: Int, regs: List[Int]) => regs.patch(C, List(A), 1)),
+
+  "gtir" -> ((A: Int, B: Int, C: Int, regs: List[Int]) => regs.patch(C, List(ifb(A, regs(B), _ > _)), 1)),
+  "gtri" -> ((A: Int, B: Int, C: Int, regs: List[Int]) => regs.patch(C, List(ifb(regs(A), B, _ > _)), 1)),
+  "gtrr" -> ((A: Int, B: Int, C: Int, regs: List[Int]) => regs.patch(C, List(ifb(regs(A), regs(B), _ > _)), 1)),
+
+  "eqir" -> ((A: Int, B: Int, C: Int, regs: List[Int]) => regs.patch(C, List(ifb(A, regs(B), _ == _)), 1)),
+  "eqri" -> ((A: Int, B: Int, C: Int, regs: List[Int]) => regs.patch(C, List(ifb(regs(A), B, _ == _)), 1)),
+  "eqrr" -> ((A: Int, B: Int, C: Int, regs: List[Int]) => regs.patch(C, List(ifb(regs(A), regs(B), _ == _)), 1))
+)
+
+type Registers = List[Int]
+
+case class Instruction(opcode: String, A: Int, B: Int, C: Int) {
+  override def toString: String = s"$opcode $A $B $C"
+}
+
+object Instruction {
+  def apply(str: String): Instruction = str.split(" ").toList match {
+    case op :: a :: b :: c :: Nil => Instruction(op, a.toInt, b.toInt, c.toInt)
+    case _ => throw new RuntimeException("Invalid input")
+  }
+}
+
+val (Some(ptr), programLines) = Iterator
+  .continually(readLine)
+  .takeWhile(_ != null)
+  .foldLeft(
+    (None : Option[Int], List.empty[Instruction])
+  ) {
+    case ((None, _), line) => (Some(line.split(" ")(1).toInt), List())
+    case ((ptr, lines), line) => (ptr, lines ++ List(Instruction(line)))
+}
+
+def executeProgram(ptr: Int, instructions: List[Instruction], regs: Registers): Registers = regs(ptr) match {
+  case p if instructions.isDefinedAt(p) =>
+    val inst = instructions(p)
+    val outputRegs = OP_CODES(inst.opcode)(inst.A, inst.B, inst.C, regs)
+    val incrPtrInRegs = outputRegs.patch(ptr, List(outputRegs(ptr) + 1), 1)
+  // println(s"ip=$ptr ${regs.mkString("[", ", ", "]")} $inst ${incrPtrInRegs.mkString("[", ", ", "]")}")
+    executeProgram(ptr, instructions, incrPtrInRegs)
+  case _ => regs
+}
+
+val endRegs = executeProgram(ptr, programLines, List.fill(6)(0))
+println(s"End value in reg 0: " + endRegs(0))
diff --git a/day2/part1.scala b/2018/day2/part1.scala
similarity index 100%
rename from day2/part1.scala
rename to 2018/day2/part1.scala
diff --git a/day2/part2.scala b/2018/day2/part2.scala
similarity index 100%
rename from day2/part2.scala
rename to 2018/day2/part2.scala
diff --git a/day20/part1.scala b/2018/day20/part1.scala
similarity index 100%
rename from day20/part1.scala
rename to 2018/day20/part1.scala
diff --git a/day3/part1.scala b/2018/day3/part1.scala
similarity index 100%
rename from day3/part1.scala
rename to 2018/day3/part1.scala
diff --git a/day3/part2.scala b/2018/day3/part2.scala
similarity index 100%
rename from day3/part2.scala
rename to 2018/day3/part2.scala
diff --git a/day4/part1.scala b/2018/day4/part1.scala
similarity index 100%
rename from day4/part1.scala
rename to 2018/day4/part1.scala
diff --git a/day4/part2.scala b/2018/day4/part2.scala
similarity index 100%
rename from day4/part2.scala
rename to 2018/day4/part2.scala
diff --git a/day5/part1.scala b/2018/day5/part1.scala
similarity index 100%
rename from day5/part1.scala
rename to 2018/day5/part1.scala
diff --git a/day5/part2.scala b/2018/day5/part2.scala
similarity index 100%
rename from day5/part2.scala
rename to 2018/day5/part2.scala
diff --git a/day6/part1.scala b/2018/day6/part1.scala
similarity index 100%
rename from day6/part1.scala
rename to 2018/day6/part1.scala
diff --git a/day6/part2.scala b/2018/day6/part2.scala
similarity index 100%
rename from day6/part2.scala
rename to 2018/day6/part2.scala
diff --git a/day7/part1.scala b/2018/day7/part1.scala
similarity index 100%
rename from day7/part1.scala
rename to 2018/day7/part1.scala
diff --git a/day7/part2.scala b/2018/day7/part2.scala
similarity index 100%
rename from day7/part2.scala
rename to 2018/day7/part2.scala
diff --git a/day8/part1.scala b/2018/day8/part1.scala
similarity index 100%
rename from day8/part1.scala
rename to 2018/day8/part1.scala
diff --git a/day8/part2.scala b/2018/day8/part2.scala
similarity index 100%
rename from day8/part2.scala
rename to 2018/day8/part2.scala
diff --git a/day9/part1.scala b/2018/day9/part1.scala
similarity index 100%
rename from day9/part1.scala
rename to 2018/day9/part1.scala
diff --git a/day9/part2.scala b/2018/day9/part2.scala
similarity index 100%
rename from day9/part2.scala
rename to 2018/day9/part2.scala