diff --git a/README.md b/README.md
index 2c7fb27..7b78d1b 100644
--- a/README.md
+++ b/README.md
@@ -5,11 +5,11 @@ This repo contains my attempt at this year's Advent of Code (2023)
I will try and do some problems (probably not all of them) in Scala
## Progress:
-#### Stars: 29 / 50
-| Mon | Tue | Wed | Thu | Fri | Sat | Sun |
-|:------------------:|:-----------------:|:------------------:|:------------------:|:------------------:|:-----------------:|:------------------:|
-| | | | | 1
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-| 4
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-| 18 | 19 | 20 | 21 | 22 | 23 | 24 |
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+#### Stars: 30 / 50
+| Mon | Tue | Wed | Thu | Fri | Sat | Sun |
+|:------------------:|:-----------------:|:------------------:|:------------------:|:------------------:|:------------------:|:------------------:|
+| | | | | 1
:star::star: | 2
:star::star: | 3
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+| 4
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+| 11
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+| 18 | 19 | 20 | 21 | 22 | 23 | 24 |
+| 25 | | | | | | |
\ No newline at end of file
diff --git a/src/day16/Puzzle2.scala b/src/day16/Puzzle2.scala
new file mode 100644
index 0000000..bbbab86
--- /dev/null
+++ b/src/day16/Puzzle2.scala
@@ -0,0 +1,136 @@
+package day16
+
+import day16.Mirrors.{DIAGONAL_BL_TR, DIAGONAL_TL_BR, Mirror, NONE, SPLITTER_HOR, SPLITTER_VER}
+
+import scala.collection.mutable.ArrayBuffer
+import scala.io.{BufferedSource, Source}
+
+object Puzzle2 {
+ var mirrors: Array[Array[Mirror]] = Array.empty
+ var energized: Array[Array[Boolean]] = Array.empty
+ var width: Int = 0
+ var height: Int = 0
+ val OFFSETS: Array[(Int, Int)] = Array(
+ (1, 0), (0, 1), (-1, 0), (0, -1)
+ )
+ var path: ArrayBuffer[(Int, Int, Int)] = new ArrayBuffer()
+
+ def loadInput(path: String): Unit = {
+ val source: BufferedSource = Source.fromFile(path)
+ val lines: Array[String] = source.getLines().toArray
+
+ height = lines.length
+ width = if (height == 0) 0 else lines(0).length
+ mirrors = Array.ofDim(height, width)
+
+ for ((line: String, y: Int) <- lines.zipWithIndex) {
+ for ((c: Char, x: Int) <- line.zipWithIndex) {
+ val mirror: Mirror = Mirrors.withName(""+c)
+ mirrors(y)(x) = mirror
+ }
+ }
+
+ source.close()
+ }
+
+ def shootBeam(startX: Int, startY: Int, startDir: Int): Unit = {
+ if (startX < 0 || startX >= width || startY < 0 || startY >= height) return
+ var x: Int = startX
+ var y: Int = startY
+ var dir: Int = startDir
+ var continue: Boolean = true
+ do {
+ if (path.contains((x, y, dir))) return
+ path.addOne((x, y, dir))
+
+ energized(y)(x) = true
+
+ mirrors(y)(x) match {
+ case NONE => {}
+ case DIAGONAL_TL_BR => {
+ dir = Math.floorDiv(dir, 2)*2 + 1 - (dir % 2)
+ }
+ case DIAGONAL_BL_TR => {
+ dir = 3 - dir
+ }
+ case SPLITTER_HOR => {
+ if (dir % 2 == 1) {
+ continue = false
+ shootBeam(x+1, y, 0)
+ shootBeam(x-1, y, 2)
+ }
+ }
+ case SPLITTER_VER => {
+ if (dir % 2 == 0) {
+ continue = false
+ shootBeam(x, y+1, 1)
+ shootBeam(x, y-1, 3)
+ }
+ }
+ }
+
+ if (continue) {
+ val offset: (Int, Int) = OFFSETS(dir)
+ x += offset._1
+ y += offset._2
+ }
+
+ if (x < 0 || x >= width) continue = false
+ if (y < 0 || y >= height) continue = false
+ } while (continue)
+ }
+
+ def countEnergized(): Int = {
+ var count: Int = 0
+ for (y: Int <- 0 until height) {
+ for (x: Int <- 0 until width) {
+ if (energized(y)(x)) count += 1
+ }
+ }
+ return count
+ }
+
+ def clearEnergized(): Unit = {
+ energized = Array.ofDim(height, width)
+ path.clear()
+ }
+
+ def solve(path: String): Int = {
+ loadInput(path)
+
+ var solution: Int = 0
+ val totalSteps: Int = (width + height)*2
+
+ for (y: Int <- 0 until height) {
+ print(f"\r${2.0*y/totalSteps*100}%.2f%%")
+ clearEnergized()
+ shootBeam(0, y, 0)
+ solution = Math.max(solution, countEnergized())
+
+ print(f"\r${(2.0*y+1)/totalSteps*100}%.2f%%")
+ clearEnergized()
+ shootBeam(width-1, y, 1)
+ solution = Math.max(solution, countEnergized())
+ }
+
+ for (x: Int <- 0 until width) {
+ print(f"\r${(2.0*x+height*2)/totalSteps*100}%.2f%%")
+ clearEnergized()
+ shootBeam(x, 0, 1)
+ solution = Math.max(solution, countEnergized())
+
+ print(f"\r${(2.0*x+height*2+1)/totalSteps*100}%.2f%%")
+ clearEnergized()
+ shootBeam(x, height-1, 3)
+ solution = Math.max(solution, countEnergized())
+ }
+ println("100%")
+
+ return solution
+ }
+
+ def main(args: Array[String]): Unit = {
+ val solution: Int = solve("./res/day16/input1.txt")
+ println(solution)
+ }
+}
diff --git a/tests/day16/Puzzle2Test.scala b/tests/day16/Puzzle2Test.scala
new file mode 100644
index 0000000..a9decb1
--- /dev/null
+++ b/tests/day16/Puzzle2Test.scala
@@ -0,0 +1,9 @@
+package day16
+
+import org.scalatest.funsuite.AnyFunSuite
+
+class Puzzle2Test extends AnyFunSuite {
+ test("Puzzle2.solve") {
+ assert(Puzzle2.solve("tests_res/day16/input1.txt") == 51)
+ }
+}