Twitter OSCON coding puzzle

sol.scala

import scala.util.Try
val nl = System.lineSeparator


def gliff(xs: String) = {
	xs.stripMargin.split(nl).to[List]
}

val gliffs =
  Map(
    gliff("""|---
             |xxx
             |---""") -> '━',

    gliff("""|-x-
             |-x-
             |-x-""") -> '┃',

    gliff("""|---
             |-xx
             |-x-""") -> '┏',

    gliff("""|---
             |xx-
             |-x-""") -> '┓',

    gliff("""|-x-
             |-xx
             |---""") -> '┗',

    gliff("""|-x-
             |xx-
             |---""") -> '┛',

    gliff("""|-x-
             |-xx
             |-x-""") -> '┣',

    gliff("""|-x-
             |xx-
             |-x-""") -> '┫',

    gliff("""|---
             |xxx
             |-x-""") -> '┳',

    gliff("""|-x-
             |xxx
             |---""") -> '┻',

    gliff("""|-x-
             |xxx
             |-x-""") -> '╋',

    gliff("""|---
             |x--
             |---""") -> '╸',


    gliff("""|-x-
             |---
             |---""") -> '╹',

    gliff("""|---
             |--x
             |---""") -> '╺',

    gliff("""|---
             |---
             |-x-""") -> '╻'
  )


def slice2d(fromX: Int, toX: Int, fromY: Int, toY: Int)(a: List[String]) = {
    a.slice(fromY, toY + 1).map(_.substring(fromX, toX + 1))
}

val omaze =
      """|-----------------------
         |-xxxxxxxxxxxxxxxxxxxxx-
         |-x---x-----x-----x-x-x-
         |-x-x-x-xxx-xxxxx-x-x-x-
         |-x-x-x---x-----x-x---x-
         |-x-xxxxxxx-x-xxx-x-x-x-
         |-x---------x-----x-x-x-
         |-x-xxx-xxxxx-xxxxx-x-x-
         |-x-x---x---x-x-----x-x-
         |-x-xxxxx-x-x-x-xxx-x---
         |-------x-x-x-x-x-x-xxx-
         |-xxxxx-x-x-x-x-x-x-x-x-
         |-x-----x-x-x---x-x-x-x-
         |-x-xxxxxxx-xxxxx-x-x-x-
         |-x-------x-------x---x-
         |-xxxxxxxxxxxxxxxxxxxxx-
         |-----------------------""".stripMargin

val maze = gliff(omaze)

def draw(maze: List[List[Char]]) = maze.map(_.mkString("")).mkString(nl)

val empty = ' '
val holes =
  (0 until maze.length).sliding(3, 1).to[List].map { case ys =>
      (0 until maze(0).length).sliding(3, 1).to[List].map { case xs =>
          val slice = slice2d(xs.head, xs.last, ys.head, ys.last)(maze)
          gliffs.getOrElse(slice, empty)
      }
  }

val east = Set('╋', '┓', '━', '┫', '┳', '╸', '┛', '┻')
val west = Set('╋', '━', '┏', '┣', '┗', '┳', '╺', '┻')
val north = Set('╋', '┓', '┏', '┃', '┣', '┫', '┳', '╻')
val south = Set('╋', '╹', '┃', '┣', '┗', '┫', '┛', '┻')

val sol =
  holes.zipWithIndex.map{ case (xs, i) =>{
      xs.zipWithIndex.map{ case (c, j) =>
          def get(x: Int, y: Int): Char = {
              Try(holes(x)(y)).getOrElse(empty)
          }     
          if(c != empty) c
          else if(north.contains(get(i-1, j)) ||
                  south.contains(get(i+1, j))) '┃'
          else if(east.contains(get(i, j+1)) ||
                  west.contains(get(i, j-1))) '━'
          else if(north.contains(get(i-2, j))) '╹'
          else if(south.contains(get(i+2, j))) '╻'
          else if(east.contains(get(i, j+2))) '╺'
          else if(west.contains(get(i, j-2))) '╸'
          else ' '
      }
  }}


draw(holes)
/*
┏ ━ ┳ ━━━ ┳ ━━━ ┳ ┳ ┓
                     
┃   ┃   ┓ ┗ ━ ┓ ┃   ┃
┃               ┃   ┃
┃ ┗ ┻ ━ ┛     ┛ ┃   ┃
┃                 ┃ ┃
┃ ┏   ┏ ━ ┫ ┏ ━ ┛ ┃ ┃
┃                 ┃  
  ┗ ━ ┫   ┃ ┃ ┏ ┓    
        ┃ ┃ ┃     ┣ ┓
┏ ━━  ┃ ┃ ┃   ┃ ┃    
                ┃ ┃ ┃
┃  ━━ ┻ ┫ ┗ ━ ┛ ┃   ┃
                     
┗ ━━━━━ ┻ ━━━━━ ┻ ━ ┛
*/

omaze.replaceAll("-", " ")
/*
xxxxxxxxxxxxxxxxxxxxx 
 x   x     x     x x x 
 x x x xxx xxxxx x x x 
 x x x   x     x x   x 
 x xxxxxxx x xxx x x x 
 x         x     x x x 
 x xxx xxxxx xxxxx x x 
 x x   x   x x     x x 
 x xxxxx x x x xxx x   
       x x x x x x xxx 
 xxxxx x x x x x x x x 
 x     x x x   x x x x 
 x xxxxxxx xxxxx x x x 
 x       x       x   x 
 xxxxxxxxxxxxxxxxxxxxx
*/

draw(sol)
/*
┏━━━┳━━━━━┳━━━━━┳━┳━┓
┃   ┃     ┃     ┃ ┃ ┃
┃ ╻ ┃ ╺━┓ ┗━━━┓ ┃ ╹ ┃
┃ ┃ ┃   ┃     ┃ ┃ ╻ ┃
┃ ┗━┻━━━┛ ╻ ╺━┛ ┃ ┃ ┃
┃         ┃     ┃ ┃ ┃
┃ ┏━╸ ┏━━━┫ ┏━━━┛ ┃ ┃
┃ ┃   ┃ ╻ ┃ ┃     ┃ ┃
┃ ┗━━━┫ ┃ ┃ ┃ ┏━┓ ┃ ╹
╹     ┃ ┃ ┃ ┃ ┃ ┃ ┣━┓
┏━━━━╸┃ ┃ ┃ ┃ ┃ ┃ ┃ ┃
┃     ┃ ┃ ┃ ╹ ┃ ┃ ┃ ┃
┃╺━━━━┻━┫ ┗━━━┛ ┃ ┃ ┃
┃       ┃       ┃ ╹ ┃
┗━━━━━━━┻━━━━━━━┻━━━┛
*/