/* The Computer Language Shootout http://shootout.alioth.debian.org/ contributed by Isaac Gouy */ // Most for-comprehension replaced by while loops // BoardCells occupied by each Piece orientation are cached // Piece orientations are cached import scala.collection.mutable._ object meteor { def main(args: Array[String]) = { val solver = new Solver( Integer.parseInt(args(0)) ) solver.findSolutions solver.printSolutions } } // Solver.scala // import scala.collection.mutable._ final class Solver (n: Int) { private var countdown = n private var first: String = _ private var last: String = _ private val board = new Board() val pieces = Array( new Piece(0), new Piece(1), new Piece(2), new Piece(3), new Piece(4), new Piece(5), new Piece(6), new Piece(7), new Piece(8), new Piece(9) ) val unplaced = new BitSet(pieces.length) { unplaced ++= (0 until pieces.length) } def findSolutions(): Unit = { if (countdown == 0) return if (unplaced.size > 0){ val emptyCellIndex = board.firstEmptyCellIndex var k = 0 while (k < pieces.length){ if (unplaced.contains(k)){ unplaced -= k var i = 0 while (i < Piece.orientations){ val piece = pieces(k).nextOrientation var j = 0 while (j < Piece.size){ if (board.add(j,emptyCellIndex,piece)) { if (!shouldPrune) findSolutions board.remove(piece) } j = j + 1 } i = i + 1 } unplaced += k } k = k + 1 } } else { puzzleSolved } } private def puzzleSolved() = { val b = board.asString if (first == null){ first = b; last = b } else { if (b < first){ first = b } else { if (b > last){ last = b } } } countdown = countdown - 1 } private def shouldPrune(): Boolean = { board.unmark var i = 0 while (i < board.cells.length){ if (board.cells(i).contiguousEmptyCells % Piece.size != 0) return true i = i + 1 } false } def printSolutions() = { def printBoard(s: String) = { var indent = false var i = 0 while (i < s.length){ if (indent) Console.print(' ') var j = 0 while (j < Board.cols){ Console.print(s.charAt(i)); Console.print(' ') j = j + 1 i = i + 1 } Console.print('\n') indent = !indent } Console.print('\n') } Console.print(n + " solutions found\n\n") printBoard(first) printBoard(last) } /* def printPieces() = for (i <- Iterator.range(0,Board.pieces)) pieces(i).print */ } // Board.scala // import scala.collection.mutable._ object Board { val cols = 5 val rows = 10 val size = rows * cols val pieces = 10 val noFit = new Array[BoardCell](0) } final class Board { val cells = boardCells() val cellsPieceWillFill = new Array[BoardCell](Piece.size) var cellCount = 0 def unmark() = { var i = 0 while (i < cells.length){ cells(i).unmark i = i + 1 } } def asString() = new String( cells map( c => if (c.piece == null) '-'.toByte else (c.piece.number + 48).toByte )) def firstEmptyCellIndex() = cells.findIndexOf(c => c.isEmpty) private val cache: Array[Array[Array[Array[ Array[BoardCell] ]]]] = for (i <- Array.range(0,Board.pieces)) yield for (j <- Array.range(0,Piece.orientations)) yield for (k <- Array.range(0,Piece.size)) // piece cell index yield for (m <- Array.range(0,Board.size)) // board cell index yield (null: BoardCell) def add(pieceIndex: Int, boardIndex: Int, p: Piece): Boolean = { var a = cache(p.number)(p.orientation)(pieceIndex)(boardIndex) cellCount = 0 p.unmark if (a == null){ find(p.cells(pieceIndex), cells(boardIndex)) if (cellCount != Piece.size){ cache(p.number)(p.orientation)(pieceIndex)(boardIndex) = Board.noFit return false } a = cellsPieceWillFill .filter(c => true) cache(p.number)(p.orientation)(pieceIndex)(boardIndex) = a } else { if (a == Board.noFit) return false } var i = 0 while (i < a.length){ if (!a(i).isEmpty) return false i = i + 1 } i = 0 while (i < a.length){ a(i).piece = p i = i + 1 } true } def remove(piece: Piece) = { var i = 0 while (i < cells.length){ if (cells(i).piece == piece) cells(i).empty i = i + 1 } } private def find(p: PieceCell, b: BoardCell): Unit = { if (p != null && !p.marked && b != null){ cellsPieceWillFill(cellCount) = b cellCount = cellCount + 1 p.mark var i = 0 while (i < Cell.sides){ find(p.next(i), b.next(i)) i = i + 1 } } } private def boardCells() = { val a = for (i <- Array.range(0,Board.size)) yield new BoardCell(i) val m = (Board.size / Board.cols) - 1 for (i <- Iterator.range(0,a.length)){ val row = i / Board.cols val isFirst = i % Board.cols == 0 val isLast = (i+1) % Board.cols == 0 val c = a(i) if (row % 2 == 1) { if (!isLast) c.next(Cell.NE) = a(i-(Board.cols-1)) c.next(Cell.NW) = a(i-Board.cols) if (row != m) { if (!isLast) c.next(Cell.SE) = a(i+(Board.cols+1)) c.next(Cell.SW) = a(i+Board.cols) } } else { if (row != 0) { if (!isFirst) c.next(Cell.NW) = a(i-(Board.cols+1)) c.next(Cell.NE) = a(i-Board.cols) } if (row != m) { if (!isFirst) c.next(Cell.SW) = a(i+(Board.cols-1)) c.next(Cell.SE) = a(i+Board.cols) } } if (!isFirst) c.next(Cell.W) = a(i-1) if (!isLast) c.next(Cell.E) = a(i+1) } a } /* // Printing all the board cells and their neighbours // helps check that they are connected properly def printBoardCellsAndNeighbours() = { Console.println("cell\tNW NE W E SW SE") for (i <- Iterator.range(0,Board.size)){ Console.print(i + "\t") for (j <- Iterator.range(0,Cell.sides)){ val c = cells(i).next(j) if (c == null) Console.print("-- ") else Console.printf("{0,number,00} ")(c.number) } Console.println("") } Console.println("") } */ } // Piece.scala object Piece { val size = 5 val rotations = Cell.sides val flips = 2 val orientations = rotations * flips } final class Piece(_number: Int) { val number = _number def unmark() = { val c = cache(orientation) var i = 0 while (i < c.length){ c(i).unmark i = i + 1 } } def cells = cache(orientation) private val cache = for (i <- Array.range(0,Piece.orientations)) yield pieceOrientation(i) var orientation = 0 def nextOrientation() = { orientation = (orientation + 1) % Piece.orientations this } private def pieceOrientation(k: Int) = { val cells = for (i <- Array.range(0,Piece.size)) yield new PieceCell() makePiece(number,cells) var i = 0 while (i < k){ if (i % Piece.rotations == 0) for (c <- cells) c.flip else for (c <- cells) c.rotate i = i + 1 } cells } private def makePiece(number: Int, cells: Array[PieceCell]) = { number match { case 0 => make0(cells) case 1 => make1(cells) case 2 => make2(cells) case 3 => make3(cells) case 4 => make4(cells) case 5 => make5(cells) case 6 => make6(cells) case 7 => make7(cells) case 8 => make8(cells) case 9 => make9(cells) } } private def make0(a: Array[PieceCell]) = { a(0).next(Cell.E) = a(1) a(1).next(Cell.W) = a(0) a(1).next(Cell.E) = a(2) a(2).next(Cell.W) = a(1) a(2).next(Cell.E) = a(3) a(3).next(Cell.W) = a(2) a(3).next(Cell.SE) = a(4) a(4).next(Cell.NW) = a(3) } private def make1(a: Array[PieceCell]) = { a(0).next(Cell.SE) = a(1) a(1).next(Cell.NW) = a(0) a(1).next(Cell.SW) = a(2) a(2).next(Cell.NE) = a(1) a(2).next(Cell.W) = a(3) a(3).next(Cell.E) = a(2) a(3).next(Cell.SW) = a(4) a(4).next(Cell.NE) = a(3) } private def make2(a: Array[PieceCell]) = { a(0).next(Cell.W) = a(1) a(1).next(Cell.E) = a(0) a(1).next(Cell.SW) = a(2) a(2).next(Cell.NE) = a(1) a(2).next(Cell.SE) = a(3) a(3).next(Cell.NW) = a(2) a(3).next(Cell.SE) = a(4) a(4).next(Cell.NW) = a(3) } private def make3(a: Array[PieceCell]) = { a(0).next(Cell.SW) = a(1) a(1).next(Cell.NE) = a(0) a(1).next(Cell.W) = a(2) a(2).next(Cell.E) = a(1) a(1).next(Cell.SW) = a(3) a(3).next(Cell.NE) = a(1) a(2).next(Cell.SE) = a(3) a(3).next(Cell.NW) = a(2) a(3).next(Cell.SE) = a(4) a(4).next(Cell.NW) = a(3) } private def make4(a: Array[PieceCell]) = { a(0).next(Cell.SE) = a(1) a(1).next(Cell.NW) = a(0) a(1).next(Cell.SW) = a(2) a(2).next(Cell.NE) = a(1) a(1).next(Cell.E) = a(3) a(3).next(Cell.W) = a(1) a(3).next(Cell.SE) = a(4) a(4).next(Cell.NW) = a(3) } private def make5(a: Array[PieceCell]) = { a(0).next(Cell.SW) = a(1) a(1).next(Cell.NE) = a(0) a(0).next(Cell.SE) = a(2) a(2).next(Cell.NW) = a(0) a(1).next(Cell.SE) = a(3) a(3).next(Cell.NW) = a(1) a(2).next(Cell.SW) = a(3) a(3).next(Cell.NE) = a(2) a(3).next(Cell.SW) = a(4) a(4).next(Cell.NE) = a(3) } private def make6(a: Array[PieceCell]) = { a(0).next(Cell.SW) = a(1) a(1).next(Cell.NE) = a(0) a(2).next(Cell.SE) = a(1) a(1).next(Cell.NW) = a(2) a(1).next(Cell.SE) = a(3) a(3).next(Cell.NW) = a(1) a(3).next(Cell.SW) = a(4) a(4).next(Cell.NE) = a(3) } private def make7(a: Array[PieceCell]) = { a(0).next(Cell.SE) = a(1) a(1).next(Cell.NW) = a(0) a(0).next(Cell.SW) = a(2) a(2).next(Cell.NE) = a(0) a(2).next(Cell.SW) = a(3) a(3).next(Cell.NE) = a(2) a(3).next(Cell.SE) = a(4) a(4).next(Cell.NW) = a(3) } private def make8(a: Array[PieceCell]) = { a(0).next(Cell.E) = a(1) a(1).next(Cell.W) = a(0) a(1).next(Cell.E) = a(2) a(2).next(Cell.W) = a(1) a(2).next(Cell.NE) = a(3) a(3).next(Cell.SW) = a(2) a(3).next(Cell.E) = a(4) a(4).next(Cell.W) = a(3) } private def make9(a: Array[PieceCell]) = { a(0).next(Cell.E) = a(1) a(1).next(Cell.W) = a(0) a(1).next(Cell.E) = a(2) a(2).next(Cell.W) = a(1) a(2).next(Cell.NE) = a(3) a(3).next(Cell.SW) = a(2) a(2).next(Cell.E) = a(4) a(4).next(Cell.W) = a(2) a(4).next(Cell.NW) = a(3) a(3).next(Cell.SE) = a(4) } /* def print() = { Console.println("Piece # " + number) Console.println("cell\tNW NE W E SW SE") for (i <- Iterator.range(0,Piece.size)){ Console.print(i + "\t") for (j <- Iterator.range(0,Cell.sides)){ val c = cells(i).next(j) if (c == null) Console.print("-- ") else for (k <- Iterator.range(0,Piece.size)){ if (cells(k) == c) Console.printf(" {0,number,0} ")(k) } } Console.println("") } Console.println("") } */ } // Cell.scala object Cell { val NW = 0; val NE = 1 val W = 2; val E = 3 val SW = 4; val SE = 5 val sides = 6 } abstract class Cell { var marked = false def mark() = marked = true def unmark() = marked = false } // BoardCell.scala final class BoardCell(_number: Int) extends Cell { val next = new Array[BoardCell](Cell.sides) val number = _number var piece: Piece = _ def isEmpty() = piece == null def empty() = piece = null def contiguousEmptyCells(): Int = { if (!marked && isEmpty){ mark var count = 1 var i = 0 while (i < next.length){ if (next(i) != null && next(i).isEmpty) count = count + next(i).contiguousEmptyCells i = i + 1 } count } else { 0 } } } // PieceCell.scala final class PieceCell extends Cell { val next = new Array[PieceCell](Cell.sides) def flip = { var swap = next(Cell.NE) next(Cell.NE) = next(Cell.NW) next(Cell.NW) = swap swap = next(Cell.E) next(Cell.E) = next(Cell.W) next(Cell.W) = swap swap = next(Cell.SE) next(Cell.SE) = next(Cell.SW) next(Cell.SW) = swap } def rotate = { var swap = next(Cell.E) next(Cell.E) = next(Cell.NE) next(Cell.NE) = next(Cell.NW) next(Cell.NW) = next(Cell.W) next(Cell.W) = next(Cell.SW) next(Cell.SW) = next(Cell.SE) next(Cell.SE) = swap } }