gistfile1.scala

abstract class Cell()
case class Space() extends Cell {
    override def toString() = " "
}
case class X() extends Cell {
    override def toString() = "X"
}
case class O() extends Cell {
    override def toString() = "O"
}

abstract class GameResult()
case class Continue() extends GameResult
case class Draw() extends GameResult
case class Win(c: Cell) extends GameResult

class Game() {
    val state: Array[Cell] = Array.fill(9)(Space())
    private var lastMove: Cell = Space()
    private var lastResult: GameResult = Continue()
    def moves(m: Array[(Int,Cell)]) = m.foreach(ic => move(ic._1, ic._2))
    def move(i: Int, c: Cell) = {
        assume( lastResult == Continue(), "game must not be over" )
        assume( state(i) == Space(), "current cell must be empty" )
        assume( c != Space(), "new cell must be nonempty" )
        assume( c != lastMove, "must alternate moves" )
        state(i) = c
        lastMove = c
        lastResult = result
        lastResult
    } 
    def winners() = {
        val r = Array.range(0, 3)
        Array(
            (for { i <- r; j <- r } yield i * 3 + j).grouped(3).toArray,
            (for { i <- r; j <- r } yield i + j * 3).grouped(3).toArray,
            (for { i <- Array(0, 2) } yield Array(0 + i, 4, 8 - i))
        ).flatten
    }
    def result(): GameResult = {
        for (w <- winners) {
            w.map(i => state(i)) match {
                case Array(x, y, z) if x != Space() && x == y && y == z => {
                    return Win(x)
                }
                case _ => ()
            }
        }
            
        if (state.exists(x => x == Space()))
            return Continue()
        return Draw()
    }
    override def toString() = {
        state.grouped(3).map(x => x.mkString("[", "", "]")).mkString("\n")
    }
}

object xoxoxo {
    def rows() = {
        val g = new Game()
        g.moves(Array(
            (0, X()),
            (4, O()),
            (8, X()),
            (2, O()),
            (6, X()),
            (3, O()),
            (7, X())));
        Console.println(g.toString)
        Console.println(g.result.toString)
    }
    def cols() = {
        val g = new Game()
        g.moves(Array(
            (0, X()),
            (4, O()),
            (8, X()),
            (2, O()),
            (6, X()),
            (7, O()),
            (3, X())));
        Console.println(g.toString)
        Console.println(g.result.toString)
    }
    def diag() = {
        val g = new Game()
        g.moves(Array(
            (0, X()),
            (2, O()),
            (8, X()),
            (1, O()),
            (4, X())
        ));
        Console.println(g.toString)
        Console.println(g.result.toString)
    }
    def main(args: Array[String]) = {
        rows
        cols
        diag
    }
}

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