day 15 puzzle 2

src/day15/Box.scala

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+package day15
+
+import scala.collection.mutable.ArrayBuffer
+
+class Box(val id: Int) {
+  var lenses: ArrayBuffer[Lens] = new ArrayBuffer()
+  var lensesLabels: ArrayBuffer[String] = new ArrayBuffer()
+
+  def addLens(lens: Lens): Unit = {
+    if (lensesLabels.contains(lens.label)) {
+      val i: Int = lensesLabels.indexOf(lens.label)
+      lenses(i) = lens
+    } else {
+      lenses.addOne(lens)
+      lensesLabels.addOne(lens.label)
+    }
+  }
+
+  def removeLens(label: String): Unit = {
+    if (lensesLabels.contains(label)) {
+      val i: Int = lensesLabels.indexOf(label)
+      lenses.remove(i)
+      lensesLabels.remove(i)
+    }
+  }
+  def getFocusingPower(): Long = {
+    var power: Long = 0
+    for ((lens: Lens, i: Int) <- lenses.zipWithIndex) {
+      power += (i+1) * lens.focalLength
+    }
+    return power
+  }
+}

src/day15/Lens.scala

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+package day15
+
+class Lens(val label: String, val focalLength: Int) {
+
+}

src/day15/Puzzle2.scala

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+package day15
+
+import scala.io.{BufferedSource, Source}
+import scala.util.matching.Regex
+import scala.util.matching.Regex.Match
+
+object Puzzle2 {
+  var steps: Array[String] = Array.empty
+  val boxes: Array[Box] = new Array(256)
+  val regex: Regex = new Regex("([a-z]+)(-|=\\d)")
+  def loadInput(path: String): Unit = {
+    val source: BufferedSource = Source.fromFile(path)
+    val line: String = source.getLines().mkString
+
+    for (i: Int <- 0 until 256) {
+      boxes(i) = new Box(i)
+    }
+
+    steps = line.split(",")
+
+    source.close()
+  }
+
+  def hash(str: String): Int = {
+    var value: Int = 0
+    for (c: Char <- str) {
+      value += c
+      value *= 17
+      value %= 256
+    }
+    return value
+  }
+
+  def getFocusingPower(): Long = {
+    var power: Long = 0
+    for (box: Box <- boxes) {
+      power += (box.id+1) * box.getFocusingPower()
+    }
+    return power
+  }
+
+  def placeLenses(): Unit = {
+    for (step: String <- steps) {
+      val m: Match = regex.findFirstMatchIn(step).get
+      val label: String = m.group(1)
+      val labelHash: Int = hash(label)
+      val action: Char = m.group(2)(0)
+      val box: Box = boxes(labelHash)
+      if (action == '=') {
+        val lens: Lens = new Lens(label, m.group(2)(1) - '0')
+        box.addLens(lens)
+      } else {
+        box.removeLens(label)
+      }
+    }
+  }
+
+  def solve(path: String): Long = {
+    loadInput(path)
+    placeLenses()
+
+    val solution: Long = getFocusingPower()
+
+    return solution
+  }
+
+  def main(args: Array[String]): Unit = {
+    val solution: Long = solve("./res/day15/input1.txt")
+    println(solution)
+  }
+}

tests/day15/Puzzle2Test.scala

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+package day15
+
+import org.scalatest.funsuite.AnyFunSuite
+
+class Puzzle2Test extends AnyFunSuite {
+  test("Puzzle2.solve") {
+    assert(Puzzle2.solve("tests_res/day15/input1.txt") == 145)
+  }
+}