day 18 puzzle 1

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: 18 / 50
+#### Stars: 30 / 50
-|        Mon        |        Tue        |        Wed        |        Thu        |        Fri        |        Sat        |        Sun        |
+|        Mon         |        Tue        |        Wed         |        Thu         |        Fri         |        Sat         |        Sun         |
-|:-----------------:|:-----------------:|:-----------------:|:-----------------:|:-----------------:|:-----------------:|:-----------------:|
+|:------------------:|:-----------------:|:------------------:|:------------------:|:------------------:|:------------------:|:------------------:|
-|                   |                   |                   |                   | 1<br>:star::star: | 2<br>:star::star: | 3<br>:star::star: |
+|                    |                   |                    |                    | 1<br>:star::star:  | 2<br>:star::star:  | 3<br>:star::star:  |
-| 4<br>:star::star: | 5<br>:star::star: | 6<br>:star::star: | 7<br>:star::star: | 8<br>:star::star: | 9<br>:star::star: |        10         |
+| 4<br>:star::star:  | 5<br>:star::star: | 6<br>:star::star:  | 7<br>:star::star:  | 8<br>:star::star:  | 9<br>:star::star:  | 10<br>:star::star: |
-|        11         |        12         |        13         |        14         |        15         |        16         |        17         |
+| 11<br>:star::star: |        12         | 13<br>:star::star: | 14<br>:star::star: | 15<br>:star::star: | 16<br>:star::star: |         17         |
-|        18         |        19         |        20         |        21         |        22         |        23         |        24         |
+|         18         |        19         |         20         |         21         |         22         |         23         |         24         |
-|        25         |                   |                   |                   |                   |                   |                   |
+|         25         |                   |                    |                    |                    |                    |                    |

src/day10/Painter.scala

@@ -0,0 +1,77 @@
+package day10
+
+import scala.collection.mutable.ArrayBuffer
+
+class Painter(startX: Int, startY: Int, excludeX: Int, excludeY: Int) extends Walker(startX, startY, excludeX, excludeY) {
+  def walk(grid: Array[Array[Byte]], zones: Array[Array[Int]], path: ArrayBuffer[(Int, Int)]): Unit = {
+    val prevX: Int = lastX
+    val prevY: Int = lastY
+    val curX: Int = x
+    val curY: Int = y
+    val curTile: Byte = grid(y)(x)
+    super.walk(grid)
+    val newX: Int = x
+    val newY: Int = y
+    val dx: Int = newX - prevX
+    val dy: Int = newY - prevY
+
+    // West-East
+    if (curTile == 5) {
+      // Going east
+      if (dx > 0) {
+        setZone(path, zones, curX, curY - 1, 1)
+        setZone(path, zones, curX, curY + 1, 2)
+
+        // Going west
+      } else {
+        setZone(path, zones, curX, curY - 1, 2)
+        setZone(path, zones, curX, curY + 1, 1)
+      }
+
+    // North-South
+    } else if (curTile == 10) {
+      // Going south
+      if (dy > 0) {
+        setZone(path, zones, curX+1, curY, 1)
+        setZone(path, zones, curX-1, curY, 2)
+
+      // Going north
+      } else {
+        setZone(path, zones, curX+1, curY, 2)
+        setZone(path, zones, curX-1, curY, 1)
+      }
+
+    // Corner
+    } else if (curTile != 15) {
+      val east: Boolean = (curTile & 1) != 0
+      val south: Boolean = (curTile & 2) != 0
+
+      val toEast: Boolean = dx > 0
+      val toSouth: Boolean = dy > 0
+
+      val offsetBottom: Boolean = east ^ toEast ^ toSouth
+      val zoneY: Boolean = !toSouth ^ east
+
+      val offsetRight: Boolean = south ^ toEast ^ toSouth
+      val zoneX: Boolean = toEast ^ south
+
+      val offsetY: Int = if (offsetBottom) 1 else -1
+      val zoneYVal: Int = if (zoneY) 2 else 1
+      setZone(path, zones, curX, curY+offsetY, zoneYVal)
+
+      val offsetX: Int = if (offsetRight) 1 else -1
+      val zoneXVal: Int = if (zoneX) 2 else 1
+      setZone(path, zones, curX+offsetX, curY, zoneXVal)
+    }
+  }
+
+  private def setZone(path: ArrayBuffer[(Int, Int)], zones: Array[Array[Int]], posX: Int, posY: Int, zone: Int): Unit = {
+    val height: Int = zones.length
+    val width: Int = if (height == 0) 0 else zones(0).length
+    if (0 <= posX && posX < width && 0 <= posY && posY < height) {
+      if (!path.contains((posX, posY))) {
+        zones(posY)(posX) = zone
+      }
+    }
+  }
+}

src/day10/Puzzle1.scala

@@ -0,0 +1,74 @@
+package day10
+
+import scala.collection.immutable.HashMap
+import scala.io.{BufferedSource, Source}
+
+object Puzzle1 {
+  var grid: Array[Array[Byte]] = Array.empty
+
+  // bits: NWSE
+  val TILES: Map[Char, Byte] = HashMap(
+    '|' -> 10,
+    '-' -> 5,
+    'L' -> 9,
+    'J' -> 12,
+    '7' -> 6,
+    'F' -> 3,
+    '.' -> 0,
+    'S' -> 15
+  )
+
+  var height: Int = 0
+  var width: Int = 0
+  var startX: Int = 0
+  var startY: Int = 0
+
+  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
+    grid = Array.ofDim(height, width)
+
+    for ((line: String, y: Int) <- lines.zipWithIndex) {
+      for ((c: Char, x: Int) <- line.zipWithIndex) {
+        grid(y)(x) = TILES(c)
+        if (c == 'S') {
+          startX = x
+          startY = y
+        }
+      }
+    }
+
+    source.close()
+  }
+
+  def calculateMaxDistance(): Int = {
+    val walker1: Walker = new Walker(startX, startY)
+    walker1.walk(grid)
+    val walker2: Walker = new Walker(startX, startY, walker1.getX(), walker1.getY())
+
+    while (walker1.getPos() != walker2.getPos()) {
+      walker2.walk(grid)
+      if (walker1.getPos() == walker2.getPos()) {
+        return walker2.getDistance()
+      }
+      walker1.walk(grid)
+    }
+    return walker1.getDistance()
+  }
+
+  def solve(path: String): Int = {
+    loadInput(path)
+
+    val solution: Int = calculateMaxDistance()
+
+    return solution
+  }
+
+  def main(args: Array[String]): Unit = {
+    val solution: Int = solve("./res/day10/input1.txt")
+    println(solution)
+  }
+}

src/day10/Puzzle2.scala

@@ -0,0 +1,195 @@
+package day10
+
+import util.Ansi
+
+import scala.collection.immutable.HashMap
+import scala.collection.mutable.ArrayBuffer
+import scala.io.{BufferedSource, Source}
+
+object Puzzle2 {
+  var grid: Array[Array[Byte]] = Array.empty
+  var zones: Array[Array[Int]] = Array.empty
+
+  // bits: NWSE
+  val TILES: Map[Char, Byte] = HashMap(
+    '|' -> 10,
+    '-' -> 5,
+    'L' -> 9,
+    'J' -> 12,
+    '7' -> 6,
+    'F' -> 3,
+    '.' -> 0,
+    'S' -> 15
+  )
+
+  val TILE_CHARS: Map[Int, Char] = HashMap(
+    10 -> '│',
+    5 -> '─',
+    9 -> '└',
+    12 -> '┘',
+    6 -> '┐',
+    3 -> '┌',
+    0 -> ' ',
+    15 -> '█'
+  )
+
+  val TILE_CHARS_BOLD: Map[Int, Char] = HashMap(
+    10 -> '┃',
+    5 -> '━',
+    9 -> '┗',
+    12 -> '┛',
+    6 -> '┓',
+    3 -> '┏',
+    0 -> ' ',
+    15 -> '█'
+  )
+
+  var height: Int = 0
+  var width: Int = 0
+  var startX: Int = 0
+  var startY: Int = 0
+  var path: ArrayBuffer[(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
+    grid = Array.ofDim(height, width)
+    zones = Array.ofDim(height, width)
+
+    for ((line: String, y: Int) <- lines.zipWithIndex) {
+      for ((c: Char, x: Int) <- line.zipWithIndex) {
+        grid(y)(x) = TILES(c)
+        if (c == 'S') {
+          startX = x
+          startY = y
+        }
+      }
+    }
+
+    source.close()
+  }
+
+  def display(): Unit = {
+    for (y: Int <- 0 until height) {
+      for (x: Int <- 0 until width) {
+        val tile: Byte = grid(y)(x)
+        val zone: Int = zones(y)(x)
+        if (zone == 1) {
+          print(Ansi.BG_RGB(163, 61, 61))
+        } else if (zone == 2) {
+          print(Ansi.BG_RGB(77, 163, 61))
+        }
+        if (path.contains((x, y))) {
+          print(Ansi.BOLD)
+          print(TILE_CHARS_BOLD(tile))
+        } else {
+          print(TILE_CHARS(tile))
+        }
+        print(Ansi.CLEAR)
+      }
+      println()
+    }
+  }
+
+  def calculateArea(): Int = {
+    path = new ArrayBuffer()
+    path.addOne((startX, startY))
+
+    val walker: Walker = new Walker(startX, startY)
+
+    do {
+      walker.walk(grid)
+      path.addOne(walker.getPos())
+    } while (walker.getX() != startX || walker.getY() != startY)
+    println(s"Found path (length = ${path.length})")
+
+    val painter: Painter = new Painter(startX, startY, 2*startX-path(1)._1, 2*startY-path(1)._2)
+    do {
+      painter.walk(grid, zones, path)
+    } while (painter.getX() != startX || painter.getY() != startY)
+    println("Painted path neighbours")
+
+    var newZones: Array[Array[Int]] = Array.ofDim(height, width)
+    var changed: Boolean = true
+    var exteriorZone: Int = 0
+
+    do {
+      changed = false
+      newZones = copyZones()
+      for (y: Int <- 0 until height) {
+        for (x: Int <- 0 until width) {
+          if (zones(y)(x) != 0) {
+            if (floodTile(x, y, newZones, path)) {
+              changed = true
+            }
+          }
+        }
+      }
+      zones = newZones
+    } while (changed)
+    println("Flooded zones")
+
+    for (y: Int <- 0 until height) {
+      for (x: Int <- 0 until width) {
+        if (x == 0 || x == width - 1 || y == 0 || y == height - 1) {
+          if (zones(y)(x) != 0) {
+            exteriorZone = zones(y)(x)
+          }
+        }
+      }
+    }
+    println(s"Found exterior zone: $exteriorZone")
+
+    var area: Int = 0
+    for (y: Int <- 0 until height) {
+      for (x: Int <- 0 until width) {
+        if (zones(y)(x) != exteriorZone && zones(y)(x) != 0) area += 1
+      }
+    }
+    println(s"Calculated area: $area")
+
+    return area
+  }
+
+  def floodTile(x: Int, y: Int, newZones: Array[Array[Int]], path: ArrayBuffer[(Int, Int)]): Boolean = {
+    var changed: Boolean = false
+    for ((dx: Int, dy: Int) <- Walker.OFFSETS) {
+      val x2: Int = x + dx
+      val y2: Int = y + dy
+      if (0 <= x2 && x2 < width && 0 <= y2 && y2 < height) {
+        if (zones(y2)(x2) == 0 && !path.contains((x2, y2))) {
+          newZones(y2)(x2) = zones(y)(x)
+          changed = true
+        }
+      }
+    }
+    return changed
+  }
+
+  def copyZones(): Array[Array[Int]] = {
+    val result: Array[Array[Int]] = Array.ofDim(height, width)
+    for (y: Int <- 0 until height) {
+      for (x: Int <- 0 until width) {
+        result(y)(x) = zones(y)(x)
+      }
+    }
+    return result
+  }
+
+  def solve(path: String): Int = {
+    loadInput(path)
+
+    val solution: Int = calculateArea()
+
+    return solution
+  }
+
+  def main(args: Array[String]): Unit = {
+    val solution: Int = solve("./res/day10/input1.txt")
+    println(solution)
+    display()
+  }
+}

src/day10/Walker.scala

@@ -0,0 +1,62 @@
+package day10
+
+class Walker {
+  protected var x: Int = 0
+  protected var y: Int = 0
+  protected var lastX: Int = -1
+  protected var lastY: Int = -1
+  protected var distance: Int = 0
+
+  def this(startX: Int, startY: Int) = {
+    this()
+    x = startX
+    y = startY
+  }
+
+  def this(startX: Int, startY: Int, excludeX: Int, excludeY: Int) = {
+    this(startX, startY)
+    lastX = excludeX
+    lastY = excludeY
+  }
+
+  def getX(): Int = x
+  def getY(): Int = y
+  def getPos(): (Int, Int) = (x, y)
+  def getDistance(): Int = distance
+
+  def walk(grid: Array[Array[Byte]]): Unit = {
+    val height: Int = grid.length
+    val width: Int = if (height == 0) 0 else grid(0).length
+    val (x2: Int, y2: Int) = getNextPos(grid, width, height)
+    lastX = x
+    lastY = y
+    x = x2
+    y = y2
+    distance += 1
+  }
+
+  private def getNextPos(grid: Array[Array[Byte]], width: Int, height: Int): (Int, Int) = {
+    val curTile: Byte = grid(y)(x)
+    for (((dx: Int, dy: Int), i: Int) <- Walker.OFFSETS.zipWithIndex) {
+      val x2: Int = x + dx
+      val y2: Int = y + dy
+      if (x2 != lastX || y2 != lastY) {
+        if (0 <= x2 && x2 < width && 0 <= y2 && y2 < height) {
+          val bit: Byte = (1 << i).toByte
+          val bit2: Byte = (1 << ((i + 2) % 4)).toByte
+          if ((curTile & bit) != 0 && (grid(y2)(x2) & bit2) != 0) {
+            return (x2, y2)
+          }
+        }
+      }
+    }
+
+    throw new Exception("Dead-end path")
+  }
+}
+
+object Walker {
+  val OFFSETS: Array[(Int, Int)] = Array(
+    (1, 0), (0, 1), (-1, 0), (0, -1)
+  )
+}

src/day11/Puzzle1.scala

@@ -0,0 +1,82 @@
+package day11
+
+import scala.collection.mutable.ArrayBuffer
+import scala.io.{BufferedSource, Source}
+
+object Puzzle1 {
+  var ogUniverse: Array[Array[Boolean]] = Array.empty
+  var ogHeight: Int = 0
+  var ogWidth: Int = 0
+  var colCounts: Array[Int] = Array.empty
+  var rowCounts: Array[Int] = Array.empty
+  var galaxies: ArrayBuffer[(Int, Int)] = new ArrayBuffer()
+  def loadInput(path: String): Unit = {
+    val source: BufferedSource = Source.fromFile(path)
+    val lines: Array[String] = source.getLines().toArray
+
+    ogHeight = lines.length
+    ogWidth = if (ogHeight == 0) 0 else lines(0).length
+    ogUniverse = Array.ofDim(ogHeight, ogWidth)
+
+    colCounts = new Array(ogWidth)
+    rowCounts = new Array(ogHeight)
+
+    for ((line: String, y: Int) <- lines.zipWithIndex) {
+      for ((c: Char, x: Int) <- line.zipWithIndex) {
+        if (c == '#') {
+          ogUniverse(y)(x) = true
+          colCounts(x) += 1
+          rowCounts(y) += 1
+        }
+      }
+    }
+
+    source.close()
+  }
+
+  def findGalaxiesRealPos(): Unit = {
+    galaxies = new ArrayBuffer()
+
+    var realX: Int = 0
+    var realY: Int = 0
+
+    for (ogY: Int <- 0 until ogHeight) {
+      realX = 0
+      for (ogX: Int <- 0 until ogWidth) {
+        if (ogUniverse(ogY)(ogX)) {
+          galaxies.addOne((realX, realY))
+        }
+        if (colCounts(ogX) == 0) realX += 1
+        realX += 1
+      }
+      if (rowCounts(ogY) == 0) realY += 1
+      realY += 1
+    }
+  }
+
+  def distance(g1: (Int, Int), g2: (Int, Int)): Int = {
+    return Math.abs(g2._1 - g1._1) + Math.abs(g2._2 - g1._2)
+  }
+
+  def solve(path: String): Int = {
+    loadInput(path)
+    findGalaxiesRealPos()
+
+    var solution: Int = 0
+
+    for (i: Int <- galaxies.indices) {
+      val g1: (Int, Int) = galaxies(i)
+      for (j: Int <- i+1 until galaxies.length) {
+        val g2: (Int, Int) = galaxies(j)
+        solution += distance(g1, g2)
+      }
+    }
+
+    return solution
+  }
+
+  def main(args: Array[String]): Unit = {
+    val solution: Int = solve("./res/day11/input1.txt")
+    println(solution)
+  }
+}

src/day11/Puzzle2.scala

@@ -0,0 +1,82 @@
+package day11
+
+import scala.collection.mutable.ArrayBuffer
+import scala.io.{BufferedSource, Source}
+
+object Puzzle2 {
+  var ogUniverse: Array[Array[Boolean]] = Array.empty
+  var ogHeight: Int = 0
+  var ogWidth: Int = 0
+  var colCounts: Array[Int] = Array.empty
+  var rowCounts: Array[Int] = Array.empty
+  var galaxies: ArrayBuffer[(Long, Long)] = new ArrayBuffer()
+  def loadInput(path: String): Unit = {
+    val source: BufferedSource = Source.fromFile(path)
+    val lines: Array[String] = source.getLines().toArray
+
+    ogHeight = lines.length
+    ogWidth = if (ogHeight == 0) 0 else lines(0).length
+    ogUniverse = Array.ofDim(ogHeight, ogWidth)
+
+    colCounts = new Array(ogWidth)
+    rowCounts = new Array(ogHeight)
+
+    for ((line: String, y: Int) <- lines.zipWithIndex) {
+      for ((c: Char, x: Int) <- line.zipWithIndex) {
+        if (c == '#') {
+          ogUniverse(y)(x) = true
+          colCounts(x) += 1
+          rowCounts(y) += 1
+        }
+      }
+    }
+
+    source.close()
+  }
+
+  def findGalaxiesRealPos(age: Int): Unit = {
+    galaxies = new ArrayBuffer()
+
+    var realX: Long = 0
+    var realY: Long = 0
+
+    for (ogY: Int <- 0 until ogHeight) {
+      realX = 0
+      for (ogX: Int <- 0 until ogWidth) {
+        if (ogUniverse(ogY)(ogX)) {
+          galaxies.addOne((realX, realY))
+        }
+        if (colCounts(ogX) == 0) realX += age-1
+        realX += 1
+      }
+      if (rowCounts(ogY) == 0) realY += age-1
+      realY += 1
+    }
+  }
+
+  def distance(g1: (Long, Long), g2: (Long, Long)): Long = {
+    return Math.abs(g2._1 - g1._1) + Math.abs(g2._2 - g1._2)
+  }
+
+  def solve(path: String, age: Int=2): Long = {
+    loadInput(path)
+    findGalaxiesRealPos(age)
+
+    var solution: Long = 0
+
+    for (i: Int <- galaxies.indices) {
+      val g1: (Long, Long) = galaxies(i)
+      for (j: Int <- i+1 until galaxies.length) {
+        val g2: (Long, Long) = galaxies(j)
+        solution += distance(g1, g2)
+      }
+    }
+
+    return solution
+  }
+
+  def main(args: Array[String]): Unit = {
+    val solution: Long = solve("./res/day11/input1.txt", 1000000)
+    println(solution)
+  }
+}

src/day13/Puzzle1.scala

@@ -0,0 +1,92 @@
+package day13
+
+import scala.io.{BufferedSource, Source}
+
+object Puzzle1 {
+  var maps: Array[Array[Array[Boolean]]] = Array.empty
+  def loadInput(path: String): Unit = {
+    val source: BufferedSource = Source.fromFile(path)
+    val lines: String = source.getLines().mkString("\n")
+
+    val mapsStr: Array[String] = lines.split("\n\n")
+    maps = new Array(mapsStr.length)
+
+    for ((mapStr: String, i: Int) <- mapsStr.zipWithIndex) {
+      val rows: Array[String] = mapStr.split("\n")
+      val map: Array[Array[Boolean]] = new Array(rows.length)
+      for ((row: String, j: Int) <- rows.zipWithIndex) {
+        map(j) = row.map(_ == '#').toArray
+      }
+      maps(i) = map
+    }
+
+    source.close()
+  }
+
+  def getReflectionValue(map: Array[Array[Boolean]]): Int = {
+    val height: Int = map.length
+    val width: Int = if (height == 0) 0 else map(0).length
+    var value: Int = 0
+
+    for (x: Int <- 0 until width-1) {
+      if (isReflection(map, x)) {
+        value += x+1
+      }
+    }
+
+    val mapT: Array[Array[Boolean]] = transpose(map)
+
+    for (y: Int <- 0 until height-1) {
+      if (isReflection(mapT, y)) {
+        value += 100*(y+1)
+      }
+    }
+
+    return value
+  }
+
+  def isReflection(map: Array[Array[Boolean]], x: Int): Boolean = {
+    for (row: Array[Boolean] <- map) {
+      val a = row.dropRight(row.length - x - 1).reverse
+      val b = row.drop(x+1)
+      for (i: Int <- 0 until Math.min(a.length, b.length)) {
+        if (a(i) != b(i)) {
+          return false
+        }
+      }
+    }
+    return true
+  }
+
+  def transpose(map: Array[Array[Boolean]]): Array[Array[Boolean]] = {
+    val height: Int = map.length
+    val width: Int = if (height == 0) 0 else map(0).length
+
+    val mapT: Array[Array[Boolean]] = Array.ofDim(width, height)
+
+    for (y: Int <- 0 until height) {
+      for (x: Int <- 0 until width) {
+        mapT(x)(y) = map(y)(x)
+      }
+    }
+
+    return mapT
+  }
+
+  def solve(path: String): Int = {
+    loadInput(path)
+
+    var solution: Int = 0
+
+    for (map: Array[Array[Boolean]] <- maps) {
+      solution += getReflectionValue(map)
+    }
+
+    return solution
+  }
+
+  def main(args: Array[String]): Unit = {
+    val solution: Int = solve("./res/day13/input1.txt")
+    println(solution)
+  }
+}

src/day13/Puzzle2.scala

@@ -0,0 +1,94 @@
+package day13
+
+import scala.io.{BufferedSource, Source}
+
+object Puzzle2 {
+  var maps: Array[Array[Array[Boolean]]] = Array.empty
+  def loadInput(path: String): Unit = {
+    val source: BufferedSource = Source.fromFile(path)
+    val lines: String = source.getLines().mkString("\n")
+
+    val mapsStr: Array[String] = lines.split("\n\n")
+    maps = new Array(mapsStr.length)
+
+    for ((mapStr: String, i: Int) <- mapsStr.zipWithIndex) {
+      val rows: Array[String] = mapStr.split("\n")
+      val map: Array[Array[Boolean]] = new Array(rows.length)
+      for ((row: String, j: Int) <- rows.zipWithIndex) {
+        map(j) = row.map(_ == '#').toArray
+      }
+      maps(i) = map
+    }
+
+    source.close()
+  }
+
+  def getReflectionValue(map: Array[Array[Boolean]]): Int = {
+    val height: Int = map.length
+    val width: Int = if (height == 0) 0 else map(0).length
+    var value: Int = 0
+
+    for (x: Int <- 0 until width-1) {
+      if (isReflection(map, x)) {
+        value += x+1
+      }
+    }
+
+    val mapT: Array[Array[Boolean]] = transpose(map)
+
+    for (y: Int <- 0 until height-1) {
+      if (isReflection(mapT, y)) {
+        value += 100*(y+1)
+      }
+    }
+
+    return value
+  }
+
+  def isReflection(map: Array[Array[Boolean]], x: Int): Boolean = {
+    var diffs: Int = 0
+    for (row: Array[Boolean] <- map) {
+      val a = row.dropRight(row.length - x - 1).reverse
+      val b = row.drop(x+1)
+      for (i: Int <- 0 until Math.min(a.length, b.length)) {
+        if (a(i) != b(i)) {
+          diffs += 1
+          if (diffs > 1) return false
+        }
+      }
+    }
+    return diffs == 1
+  }
+
+  def transpose(map: Array[Array[Boolean]]): Array[Array[Boolean]] = {
+    val height: Int = map.length
+    val width: Int = if (height == 0) 0 else map(0).length
+
+    val mapT: Array[Array[Boolean]] = Array.ofDim(width, height)
+
+    for (y: Int <- 0 until height) {
+      for (x: Int <- 0 until width) {
+        mapT(x)(y) = map(y)(x)
+      }
+    }
+
+    return mapT
+  }
+
+  def solve(path: String): Int = {
+    loadInput(path)
+
+    var solution: Int = 0
+
+    for (map: Array[Array[Boolean]] <- maps) {
+      solution += getReflectionValue(map)
+    }
+
+    return solution
+  }
+
+  def main(args: Array[String]): Unit = {
+    val solution: Int = solve("./res/day13/input1.txt")
+    println(solution)
+  }
+}

src/day14/Puzzle1.scala

@@ -0,0 +1,68 @@
+package day14
+
+import scala.io.{BufferedSource, Source}
+
+object Puzzle1 {
+  val CHARS: Array[Char] = Array('.', 'O', '#')
+  var platform: Array[Array[Int]] = Array.empty
+  var width: Int = 0
+  var height: Int = 0
+
+  def loadInput(path: String): Unit = {
+    val source: BufferedSource = Source.fromFile(path)
+    val lines: Array[String] = source.getLines().toArray
+
+    platform = lines.map(_.map(CHARS.indexOf(_)).toArray)
+    height = platform.length
+    width = if (height == 0) 0 else platform(0).length
+
+    source.close()
+  }
+
+  def slideUp(): Unit = {
+    for (y: Int <- 0 until height) {
+      for (x: Int <- 0 until width) {
+        if (platform(y)(x) == 1) {
+          slideRockUp(x, y)
+        }
+      }
+    }
+  }
+
+  def slideRockUp(x: Int, y: Int): Unit = {
+    platform(y)(x) = 0
+    for (y2: Int <- y-1 to 0 by -1) {
+      if (platform(y2)(x) != 0) {
+        platform(y2+1)(x) = 1
+        return
+      }
+    }
+    platform(0)(x) = 1
+  }
+
+  def computeLoad(): Int = {
+    var load: Int = 0
+    for (y: Int <- 0 until height) {
+      for (x: Int <- 0 until width) {
+        if (platform(y)(x) == 1) {
+          load += height-y
+        }
+      }
+    }
+    return load
+  }
+
+  def solve(path: String): Int = {
+    loadInput(path)
+    slideUp()
+
+    val solution: Int = computeLoad()
+
+    return solution
+  }
+
+  def main(args: Array[String]): Unit = {
+    val solution: Int = solve("./res/day14/input1.txt")
+    println(solution)
+  }
+}

src/day14/Puzzle2.scala

@@ -0,0 +1,153 @@
+package day14
+
+import scala.collection.mutable.ArrayBuffer
+import scala.io.{BufferedSource, Source}
+
+object Puzzle2 {
+  val CHARS: Array[Char] = Array('.', 'O', '#')
+  var platform: Array[Array[Int]] = Array.empty
+  var prevPlatform: Array[Array[Int]] = Array.empty
+  var history: ArrayBuffer[Array[Array[Int]]] = new ArrayBuffer()
+  var width: Int = 0
+  var height: Int = 0
+
+  def loadInput(path: String): Unit = {
+    val source: BufferedSource = Source.fromFile(path)
+    val lines: Array[String] = source.getLines().toArray
+
+    platform = lines.map(_.map(CHARS.indexOf(_)).toArray)
+    height = platform.length
+    width = if (height == 0) 0 else platform(0).length
+    prevPlatform = Array.ofDim(height, width)
+
+    source.close()
+  }
+
+  def slideUp(): Unit = {
+    for (y: Int <- 0 until height) {
+      for (x: Int <- 0 until width) {
+        if (platform(y)(x) == 1) {
+          slideRockUp(x, y)
+        }
+      }
+    }
+  }
+
+  def slideRockUp(x: Int, y: Int): Unit = {
+    platform(y)(x) = 0
+    for (y2: Int <- y-1 to 0 by -1) {
+      if (platform(y2)(x) != 0) {
+        platform(y2+1)(x) = 1
+        return
+      }
+    }
+    platform(0)(x) = 1
+  }
+
+  def rotate(): Unit = {
+    val result: Array[Array[Int]] = Array.ofDim(width, height)
+    width += height
+    height = width - height
+    width = width - height
+
+    for (y: Int <- 0 until height) {
+      for (x: Int <- 0 until width) {
+        result(y)(x) = platform(width-x-1)(y)
+      }
+    }
+    platform = result
+  }
+
+  def cycle(): Unit = {
+    slideUp()
+    rotate()
+    slideUp()
+    rotate()
+    slideUp()
+    rotate()
+    slideUp()
+    rotate()
+  }
+
+  def copyPlatform(): Array[Array[Int]] = {
+    val result: Array[Array[Int]] = Array.ofDim(height, width)
+    for (y: Int <- 0 until height) {
+      for (x: Int <- 0 until width) {
+        result(y)(x) = platform(y)(x)
+      }
+    }
+    return result
+  }
+
+  def computeLoad(): Int = {
+    var load: Int = 0
+    for (y: Int <- 0 until height) {
+      for (x: Int <- 0 until width) {
+        if (platform(y)(x) == 1) {
+          load += height-y
+        }
+      }
+    }
+    return load
+  }
+
+  def getLoopStart(): Int = {
+    for ((prevPlatform: Array[Array[Int]], i: Int) <- history.zipWithIndex) {
+      if (noChange(prevPlatform)) return i
+    }
+    return -1
+  }
+
+  def noChange(prevPlatform: Array[Array[Int]]): Boolean = {
+    for (y: Int <- 0 until height) {
+      for (x: Int <- 0 until width) {
+        if (prevPlatform(y)(x) != platform(y)(x)) {
+          return false
+        }
+      }
+    }
+    return true
+  }
+
+  def hasLooped(): Boolean = getLoopStart() != -1
+
+  def repeatCycle(count: Int): Unit = {
+    for (i: Int <- 0 until count) {
+      history.prepend(copyPlatform())
+      cycle()
+      //display()
+      if (hasLooped()) {
+        val loopStart: Int = getLoopStart()
+        val loopOffset: Int = (count - i - 1) % (loopStart + 1)
+        val finalI: Int = loopStart - loopOffset
+
+        platform = history(finalI)
+        return
+      }
+    }
+  }
+
+  def display(): Unit = {
+    for (y: Int <- 0 until height) {
+      for (x: Int <- 0 until width) {
+        print(CHARS(platform(y)(x)))
+      }
+      println()
+    }
+    println()
+  }
+
+  def solve(path: String, cycles: Int): Int = {
+    loadInput(path)
+    repeatCycle(cycles)
+
+    val solution: Int = computeLoad()
+
+    return solution
+  }
+
+  def main(args: Array[String]): Unit = {
+    val solution: Int = solve("./res/day14/input1.txt", 1000000000)
+    println(solution)
+  }
+}

src/day15/Box.scala

@@ -0,0 +1,33 @@
+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

@@ -0,0 +1,5 @@
+package day15
+
+class Lens(val label: String, val focalLength: Int) {
+
+}

src/day15/Puzzle1.scala

@@ -0,0 +1,42 @@
+package day15
+
+import scala.io.{BufferedSource, Source}
+
+object Puzzle1 {
+  var values: Array[String] = Array.empty
+  def loadInput(path: String): Unit = {
+    val source: BufferedSource = Source.fromFile(path)
+    val line: String = source.getLines().mkString
+
+    values = 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 solve(path: String): Int = {
+    loadInput(path)
+
+    var solution: Int = 0
+
+    for (value: String <- values) {
+      solution += hash(value)
+    }
+
+    return solution
+  }
+
+  def main(args: Array[String]): Unit = {
+    val solution: Int = solve("./res/day15/input1.txt")
+    println(solution)
+  }
+}

src/day15/Puzzle2.scala

@@ -0,0 +1,71 @@
+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)
+  }
+}

src/day16/Mirrors.scala

@@ -0,0 +1,10 @@
+package day16
+
+object Mirrors extends Enumeration {
+  type Mirror = Value
+  val NONE = Value(".")
+  val DIAGONAL_TL_BR = Value("\\")
+  val DIAGONAL_BL_TR = Value("/")
+  val SPLITTER_HOR = Value("-")
+  val SPLITTER_VER = Value("|")
+}

src/day16/Puzzle1.scala

@@ -0,0 +1,103 @@
+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 Puzzle1 {
+  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)
+  )
+  val 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)
+    energized = 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 solve(path: String): Int = {
+    loadInput(path)
+    shootBeam(0, 0, 0)
+
+    var solution: Int = 0
+
+    for (y: Int <- 0 until height) {
+      for (x: Int <- 0 until width) {
+        if (energized(y)(x)) solution += 1
+      }
+    }
+
+    return solution
+  }
+
+  def main(args: Array[String]): Unit = {
+    val solution: Int = solve("./res/day16/input1.txt")
+    println(solution)
+  }
+}

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)
+  }
+}

src/day18/Painter.scala

@@ -0,0 +1,77 @@
+package day18
+
+import scala.collection.mutable.ArrayBuffer
+
+class Painter(startX: Int, startY: Int, excludeX: Int, excludeY: Int) extends Walker(startX, startY, excludeX, excludeY) {
+  def walk(grid: Array[Array[Byte]], zones: Array[Array[Int]], path: ArrayBuffer[(Int, Int)]): Unit = {
+    val prevX: Int = lastX
+    val prevY: Int = lastY
+    val curX: Int = x
+    val curY: Int = y
+    val curTile: Byte = grid(y)(x)
+    super.walk(grid)
+    val newX: Int = x
+    val newY: Int = y
+    val dx: Int = newX - prevX
+    val dy: Int = newY - prevY
+
+    // West-East
+    if (curTile == 5) {
+      // Going east
+      if (dx > 0) {
+        setZone(path, zones, curX, curY - 1, 1)
+        setZone(path, zones, curX, curY + 1, 2)
+
+        // Going west
+      } else {
+        setZone(path, zones, curX, curY - 1, 2)
+        setZone(path, zones, curX, curY + 1, 1)
+      }
+
+    // North-South
+    } else if (curTile == 10) {
+      // Going south
+      if (dy > 0) {
+        setZone(path, zones, curX+1, curY, 1)
+        setZone(path, zones, curX-1, curY, 2)
+
+      // Going north
+      } else {
+        setZone(path, zones, curX+1, curY, 2)
+        setZone(path, zones, curX-1, curY, 1)
+      }
+
+    // Corner
+    } else if (curTile != 15) {
+      val east: Boolean = (curTile & 1) != 0
+      val south: Boolean = (curTile & 2) != 0
+
+      val toEast: Boolean = dx > 0
+      val toSouth: Boolean = dy > 0
+
+      val offsetBottom: Boolean = east ^ toEast ^ toSouth
+      val zoneY: Boolean = !toSouth ^ east
+
+      val offsetRight: Boolean = south ^ toEast ^ toSouth
+      val zoneX: Boolean = toEast ^ south
+
+      val offsetY: Int = if (offsetBottom) 1 else -1
+      val zoneYVal: Int = if (zoneY) 2 else 1
+      setZone(path, zones, curX, curY+offsetY, zoneYVal)
+
+      val offsetX: Int = if (offsetRight) 1 else -1
+      val zoneXVal: Int = if (zoneX) 2 else 1
+      setZone(path, zones, curX+offsetX, curY, zoneXVal)
+    }
+  }
+
+  private def setZone(path: ArrayBuffer[(Int, Int)], zones: Array[Array[Int]], posX: Int, posY: Int, zone: Int): Unit = {
+    val height: Int = zones.length
+    val width: Int = if (height == 0) 0 else zones(0).length
+    if (0 <= posX && posX < width && 0 <= posY && posY < height) {
+      if (!path.contains((posX, posY))) {
+        zones(posY)(posX) = zone
+      }
+    }
+  }
+}

src/day18/Puzzle1.scala

@@ -0,0 +1,234 @@
+package day18
+
+import util.Ansi
+
+import scala.collection.immutable.HashMap
+import scala.collection.mutable.ArrayBuffer
+import scala.io.{BufferedSource, Source}
+
+object Puzzle1 {
+  var grid: Array[Array[Byte]] = Array.empty
+  var zones: Array[Array[Int]] = Array.empty
+
+  val OFFSETS: Array[(Int, Int)] = Array(
+    (1, 0), (0, 1), (-1, 0), (0, -1)
+  )
+  val DIRS: String = "RDLU"
+
+  // bits: NWSE
+  val TILES: Map[Char, Byte] = HashMap(
+    '|' -> 10,
+    '-' -> 5,
+    'L' -> 9,
+    'J' -> 12,
+    '7' -> 6,
+    'F' -> 3,
+    '.' -> 0,
+    'S' -> 15
+  )
+
+  val TILE_CHARS: Map[Int, Char] = HashMap(
+    10 -> '│',
+    5 -> '─',
+    9 -> '└',
+    12 -> '┘',
+    6 -> '┐',
+    3 -> '┌',
+    0 -> ' ',
+    15 -> '█'
+  )
+
+  val TILE_CHARS_BOLD: Map[Int, Char] = HashMap(
+    10 -> '┃',
+    5 -> '━',
+    9 -> '┗',
+    12 -> '┛',
+    6 -> '┓',
+    3 -> '┏',
+    0 -> ' ',
+    15 -> '█'
+  )
+
+  var height: Int = 0
+  var width: Int = 0
+  var startX: Int = 0
+  var startY: Int = 0
+  var path: ArrayBuffer[(Int, Int)] = new ArrayBuffer()
+
+  def loadInput(path: String): Unit = {
+    val source: BufferedSource = Source.fromFile(path)
+    val lines: Array[String] = source.getLines().toArray
+
+    var x: Int = 0
+    var y: Int = 0
+
+    var minX: Int = 0
+    var minY: Int = 0
+    var maxX: Int = 0
+    var maxY: Int = 0
+
+    for (line: String <- lines) {
+      val parts: Array[String] = line.split(" ")
+      val dir: Int = DIRS.indexOf(parts(0))
+      val dist: Int = parts(1).toInt
+      val offset: (Int, Int) = OFFSETS(dir)
+      x += offset._1*dist
+      y += offset._2*dist
+      minX = math.min(minX, x)
+      minY = math.min(minY, y)
+      maxX = math.max(maxX, x)
+      maxY = math.max(maxY, y)
+    }
+
+    width = maxX - minX + 1
+    height = maxY - minY + 1
+
+    grid = Array.ofDim(height, width)
+    zones = Array.ofDim(height, width)
+
+    x = -minX
+    y = -minY
+    var prevDir: Int = DIRS.indexOf(lines.last.split(" ")(0))
+    startX = x
+    startY = y
+
+    for ((line: String, i: Int) <- lines.zipWithIndex) {
+      val parts: Array[String] = line.split(" ")
+      val dir: Int = DIRS.indexOf(parts(0))
+      val dist: Int = parts(1).toInt
+      val offset: (Int, Int) = OFFSETS(dir)
+
+      for (_: Int <- 0 until dist) {
+        val prevBit: Int = 1 << ((prevDir + 2) % 4)
+        val curBit: Int = 1 << dir
+        grid(y)(x) = (prevBit| curBit).toByte
+        x += offset._1
+        y += offset._2
+        prevDir = dir
+      }
+    }
+
+    source.close()
+  }
+
+  def display(): Unit = {
+    for (y: Int <- 0 until height) {
+      for (x: Int <- 0 until width) {
+        val tile: Byte = grid(y)(x)
+        val zone: Int = zones(y)(x)
+        if (zone == 1) {
+          print(Ansi.BG_RGB(163, 61, 61))
+        } else if (zone == 2) {
+          print(Ansi.BG_RGB(77, 163, 61))
+        }
+        if (path.contains((x, y))) {
+          print(Ansi.BOLD)
+          print(TILE_CHARS_BOLD(tile))
+        } else {
+          print(TILE_CHARS(tile))
+        }
+        print(Ansi.CLEAR)
+      }
+      println()
+    }
+  }
+
+  def calculateArea(): Int = {
+    path = new ArrayBuffer()
+    path.addOne((startX, startY))
+
+    val walker: Walker = new Walker(startX, startY)
+
+    do {
+      walker.walk(grid)
+      path.addOne(walker.getPos())
+    } while (walker.getX() != startX || walker.getY() != startY)
+    println(s"Found path (length = ${path.length})")
+
+    val painter: Painter = new Painter(startX, startY, 2*startX-path(1)._1, 2*startY-path(1)._2)
+    do {
+      painter.walk(grid, zones, path)
+    } while (painter.getX() != startX || painter.getY() != startY)
+    println("Painted path neighbours")
+
+    var newZones: Array[Array[Int]] = Array.ofDim(height, width)
+    var changed: Boolean = true
+    var exteriorZone: Int = 0
+
+    do {
+      changed = false
+      newZones = copyZones()
+      for (y: Int <- 0 until height) {
+        for (x: Int <- 0 until width) {
+          if (zones(y)(x) != 0) {
+            if (floodTile(x, y, newZones, path)) {
+              changed = true
+            }
+          }
+        }
+      }
+      zones = newZones
+    } while (changed)
+    println("Flooded zones")
+
+    for (y: Int <- 0 until height) {
+      for (x: Int <- 0 until width) {
+        if (x == 0 || x == width - 1 || y == 0 || y == height - 1) {
+          if (zones(y)(x) != 0) {
+            exteriorZone = zones(y)(x)
+          }
+        }
+      }
+    }
+    println(s"Found exterior zone: $exteriorZone")
+
+    var area: Int = 0
+    for (y: Int <- 0 until height) {
+      for (x: Int <- 0 until width) {
+        if (zones(y)(x) != exteriorZone) area += 1
+      }
+    }
+    println(s"Calculated area: $area")
+
+    return area
+  }
+
+  def floodTile(x: Int, y: Int, newZones: Array[Array[Int]], path: ArrayBuffer[(Int, Int)]): Boolean = {
+    var changed: Boolean = false
+    for ((dx: Int, dy: Int) <- Walker.OFFSETS) {
+      val x2: Int = x + dx
+      val y2: Int = y + dy
+      if (0 <= x2 && x2 < width && 0 <= y2 && y2 < height) {
+        if (zones(y2)(x2) == 0 && !path.contains((x2, y2))) {
+          newZones(y2)(x2) = zones(y)(x)
+          changed = true
+        }
+      }
+    }
+    return changed
+  }
+
+  def copyZones(): Array[Array[Int]] = {
+    val result: Array[Array[Int]] = Array.ofDim(height, width)
+    for (y: Int <- 0 until height) {
+      for (x: Int <- 0 until width) {
+        result(y)(x) = zones(y)(x)
+      }
+    }
+    return result
+  }
+
+  def solve(path: String): Int = {
+    loadInput(path)
+
+    val solution: Int = calculateArea()
+
+    return solution
+  }
+
+  def main(args: Array[String]): Unit = {
+    val solution: Int = solve("./res/day18/input1.txt")
+    println(solution)
+    //display()
+  }
+}

src/day18/Walker.scala

@@ -0,0 +1,62 @@
+package day18
+
+class Walker {
+  protected var x: Int = 0
+  protected var y: Int = 0
+  protected var lastX: Int = -1
+  protected var lastY: Int = -1
+  protected var distance: Int = 0
+
+  def this(startX: Int, startY: Int) = {
+    this()
+    x = startX
+    y = startY
+  }
+
+  def this(startX: Int, startY: Int, excludeX: Int, excludeY: Int) = {
+    this(startX, startY)
+    lastX = excludeX
+    lastY = excludeY
+  }
+
+  def getX(): Int = x
+  def getY(): Int = y
+  def getPos(): (Int, Int) = (x, y)
+  def getDistance(): Int = distance
+
+  def walk(grid: Array[Array[Byte]]): Unit = {
+    val height: Int = grid.length
+    val width: Int = if (height == 0) 0 else grid(0).length
+    val (x2: Int, y2: Int) = getNextPos(grid, width, height)
+    lastX = x
+    lastY = y
+    x = x2
+    y = y2
+    distance += 1
+  }
+
+  private def getNextPos(grid: Array[Array[Byte]], width: Int, height: Int): (Int, Int) = {
+    val curTile: Byte = grid(y)(x)
+    for (((dx: Int, dy: Int), i: Int) <- Walker.OFFSETS.zipWithIndex) {
+      val x2: Int = x + dx
+      val y2: Int = y + dy
+      if (x2 != lastX || y2 != lastY) {
+        if (0 <= x2 && x2 < width && 0 <= y2 && y2 < height) {
+          val bit: Byte = (1 << i).toByte
+          val bit2: Byte = (1 << ((i + 2) % 4)).toByte
+          if ((curTile & bit) != 0 && (grid(y2)(x2) & bit2) != 0) {
+            return (x2, y2)
+          }
+        }
+      }
+    }
+
+    throw new Exception("Dead-end path")
+  }
+}
+
+object Walker {
+  val OFFSETS: Array[(Int, Int)] = Array(
+    (1, 0), (0, 1), (-1, 0), (0, -1)
+  )
+}

src/util/Ansi.scala

@@ -0,0 +1,19 @@
+package util
+
+object Ansi {
+  val ESC: String = "\u001b["
+  val CLEAR: String = code("0")
+  val BOLD: String = code("1")
+  val FAINT: String = code("2")
+  val ITALIC: String = code("3")
+  val UNDERLINE: String = code("4")
+  val SLOW_BLINK: String = code("5")
+  val RAPID_BLINK: String = code("6")
+  val REVERSE: String = code("7")
+  val CONCEAL: String = code("8")
+  val STRIKETHROUGH: String = code("9")
+  def FG_RGB(r: Int, g: Int, b: Int): String = code(s"38;2;$r;$g;${b}")
+  def BG_RGB(r: Int, g: Int, b: Int): String = code(s"48;2;$r;$g;${b}")
+
+  private def code(str: String): String = ESC+str+"m"
+}

tests/day10/Puzzle1Test.scala

@@ -0,0 +1,12 @@
+package day10
+
+import org.scalatest.funsuite.AnyFunSuite
+
+class Puzzle1Test extends AnyFunSuite {
+  test("Puzzle1.solve 1") {
+    assert(Puzzle1.solve("tests_res/day10/input1.txt") == 4)
+  }
+  test("Puzzle1.solve 2") {
+    assert(Puzzle1.solve("tests_res/day10/input2.txt") == 8)
+  }
+}

tests/day10/Puzzle2Test.scala

@@ -0,0 +1,24 @@
+package day10
+
+import org.scalatest.funsuite.AnyFunSuite
+
+class Puzzle2Test extends AnyFunSuite {
+  test("Puzzle2.solve 1") {
+    assert(Puzzle2.solve("tests_res/day10/input1.txt") == 1)
+  }
+  test("Puzzle2.solve 2") {
+    assert(Puzzle2.solve("tests_res/day10/input2.txt") == 1)
+  }
+  test("Puzzle2.solve 3") {
+    assert(Puzzle2.solve("tests_res/day10/input3.txt") == 4)
+  }
+  test("Puzzle2.solve 4") {
+    assert(Puzzle2.solve("tests_res/day10/input4.txt") == 4)
+  }
+  test("Puzzle2.solve 5") {
+    assert(Puzzle2.solve("tests_res/day10/input5.txt") == 8)
+  }
+  test("Puzzle2.solve 6") {
+    assert(Puzzle2.solve("tests_res/day10/input6.txt") == 10)
+  }
+}

tests/day11/Puzzle1Test.scala

@@ -0,0 +1,9 @@
+package day11
+
+import org.scalatest.funsuite.AnyFunSuite
+
+class Puzzle1Test extends AnyFunSuite {
+  test("Puzzle1.solve") {
+    assert(Puzzle1.solve("tests_res/day11/input1.txt") == 374)
+  }
+}

tests/day11/Puzzle2Test.scala

@@ -0,0 +1,12 @@
+package day11
+
+import org.scalatest.funsuite.AnyFunSuite
+
+class Puzzle2Test extends AnyFunSuite {
+  test("Puzzle2.solve 1") {
+    assert(Puzzle2.solve("tests_res/day11/input1.txt", 10) == 1030)
+  }
+  test("Puzzle2.solve 2") {
+    assert(Puzzle2.solve("tests_res/day11/input1.txt", 100) == 8410)
+  }
+}

tests/day13/Puzzle1Test.scala

@@ -0,0 +1,9 @@
+package day13
+
+import org.scalatest.funsuite.AnyFunSuite
+
+class Puzzle1Test extends AnyFunSuite {
+  test("Puzzle1.solve") {
+    assert(Puzzle1.solve("tests_res/day13/input1.txt") == 405)
+  }
+}

tests/day13/Puzzle2Test.scala

@@ -0,0 +1,9 @@
+package day13
+
+import org.scalatest.funsuite.AnyFunSuite
+
+class Puzzle2Test extends AnyFunSuite {
+  test("Puzzle2.solve") {
+    assert(Puzzle2.solve("tests_res/day13/input1.txt") == 400)
+  }
+}

tests/day14/Puzzle1Test.scala

@@ -0,0 +1,9 @@
+package day14
+
+import org.scalatest.funsuite.AnyFunSuite
+
+class Puzzle1Test extends AnyFunSuite {
+  test("Puzzle1.solve") {
+    assert(Puzzle1.solve("tests_res/day14/input1.txt") == 136)
+  }
+}

tests/day14/Puzzle2Test.scala

@@ -0,0 +1,9 @@
+package day14
+
+import org.scalatest.funsuite.AnyFunSuite
+
+class Puzzle2Test extends AnyFunSuite {
+  test("Puzzle2.solve") {
+    assert(Puzzle2.solve("tests_res/day14/input1.txt", 1000000000) == 64)
+  }
+}

tests/day15/Puzzle1Test.scala

@@ -0,0 +1,9 @@
+package day15
+
+import org.scalatest.funsuite.AnyFunSuite
+
+class Puzzle1Test extends AnyFunSuite {
+  test("Puzzle1.solve") {
+    assert(Puzzle1.solve("tests_res/day15/input1.txt") == 1320)
+  }
+}

tests/day15/Puzzle2Test.scala

@@ -0,0 +1,9 @@
+package day15
+
+import org.scalatest.funsuite.AnyFunSuite
+
+class Puzzle2Test extends AnyFunSuite {
+  test("Puzzle2.solve") {
+    assert(Puzzle2.solve("tests_res/day15/input1.txt") == 145)
+  }
+}

tests/day16/Puzzle1Test.scala

@@ -0,0 +1,9 @@
+package day16
+
+import org.scalatest.funsuite.AnyFunSuite
+
+class Puzzle1Test extends AnyFunSuite {
+  test("Puzzle1.solve") {
+    assert(Puzzle1.solve("tests_res/day16/input1.txt") == 46)
+  }
+}

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)
+  }
+}

tests/day18/Puzzle1Test.scala

@@ -0,0 +1,9 @@
+package day18
+
+import org.scalatest.funsuite.AnyFunSuite
+
+class Puzzle1Test extends AnyFunSuite {
+  test("Puzzle1.solve") {
+    assert(Puzzle1.solve("tests_res/day18/input1.txt") == 62)
+  }
+}

tests_res/day10/input1.txt

@@ -0,0 +1,5 @@
+.....
+.S-7.
+.|.|.
+.L-J.
+.....

tests_res/day10/input2.txt

@@ -0,0 +1,5 @@
+..F7.
+.FJ|.
+SJ.L7
+|F--J
+LJ...

tests_res/day10/input3.txt

@@ -0,0 +1,9 @@
+...........
+.S-------7.
+.|F-----7|.
+.||.....||.
+.||.....||.
+.|L-7.F-J|.
+.|..|.|..|.
+.L--J.L--J.
+...........

tests_res/day10/input4.txt

@@ -0,0 +1,9 @@
+..........
+.S------7.
+.|F----7|.
+.||....||.
+.||....||.
+.|L-7F-J|.
+.|..||..|.
+.L--JL--J.
+..........

tests_res/day10/input5.txt

@@ -0,0 +1,10 @@
+.F----7F7F7F7F-7....
+.|F--7||||||||FJ....
+.||.FJ||||||||L7....
+FJL7L7LJLJ||LJ.L-7..
+L--J.L7...LJS7F-7L7.
+....F-J..F7FJ|L7L7L7
+....L7.F7||L7|.L7L7|
+.....|FJLJ|FJ|F7|.LJ
+....FJL-7.||.||||...
+....L---J.LJ.LJLJ...

tests_res/day10/input6.txt

@@ -0,0 +1,10 @@
+FF7FSF7F7F7F7F7F---7
+L|LJ||||||||||||F--J
+FL-7LJLJ||||||LJL-77
+F--JF--7||LJLJ7F7FJ-
+L---JF-JLJ.||-FJLJJ7
+|F|F-JF---7F7-L7L|7|
+|FFJF7L7F-JF7|JL---7
+7-L-JL7||F7|L7F-7F7|
+L.L7LFJ|||||FJL7||LJ
+L7JLJL-JLJLJL--JLJ.L

tests_res/day11/input1.txt

@@ -0,0 +1,10 @@
+...#......
+.......#..
+#.........
+..........
+......#...
+.#........
+.........#
+..........
+.......#..
+#...#.....

tests_res/day13/input1.txt

@@ -0,0 +1,15 @@
+#.##..##.
+..#.##.#.
+##......#
+##......#
+..#.##.#.
+..##..##.
+#.#.##.#.
+
+#...##..#
+#....#..#
+..##..###
+#####.##.
+#####.##.
+..##..###
+#....#..#

tests_res/day14/input1.txt

@@ -0,0 +1,10 @@
+O....#....
+O.OO#....#
+.....##...
+OO.#O....O
+.O.....O#.
+O.#..O.#.#
+..O..#O..O
+.......O..
+#....###..
+#OO..#....

tests_res/day15/input1.txt

@@ -0,0 +1 @@
+rn=1,cm-,qp=3,cm=2,qp-,pc=4,ot=9,ab=5,pc-,pc=6,ot=7

tests_res/day16/input1.txt

@@ -0,0 +1,10 @@
+.|...\....
+|.-.\.....
+.....|-...
+........|.
+..........
+.........\
+..../.\\..
+.-.-/..|..
+.|....-|.\
+..//.|....

tests_res/day18/input1.txt

@@ -0,0 +1,14 @@
+R 6 (#70c710)
+D 5 (#0dc571)
+L 2 (#5713f0)
+D 2 (#d2c081)
+R 2 (#59c680)
+D 2 (#411b91)
+L 5 (#8ceee2)
+U 2 (#caa173)
+L 1 (#1b58a2)
+U 2 (#caa171)
+R 2 (#7807d2)
+U 3 (#a77fa3)
+L 2 (#015232)
+U 2 (#7a21e3)