Google Codejam 2013 - Qualification Round - Problem 1

// Iraklis Karagkiozoglou <i.kar@windowslive.com>
// Solution to Google CodeJam 2013 Qualification Round - Problem 1
object TicTacToeTomek {
    def solve(arr: List[List[Char]]) : String = {
        def checkWin(a: List[Char]) : String = {
            val o = a.filter(c=>c=='O').length
            val x = a.filter(c=>c=='X').length
            val t = a.filter(c=>c=='T').length
            if(o+t==4) return "O won"
            else if(x+t==4) return "X won"
            else return null
        }
        for(i<-0.to(3)) {
            val h = arr(i)
            val hres = checkWin(h)
            if(hres!=null) return hres
            val v = List(arr(0)(i),arr(1)(i),arr(2)(i),arr(3)(i))
            val vres = checkWin(v)
            if(vres!=null) return vres
        }
        val d1 =  List(arr(0)(0),arr(1)(1),arr(2)(2),arr(3)(3))
        val d1res = checkWin(d1)
        if(d1res!=null) return d1res
        val d2 =   List (arr(0)(3),arr(1)(2),arr(2)(1),arr(3)(0))
        val d2res = checkWin(d2)
        if(d2res!=null) return d2res
        arr.foreach(a=>a.foreach(c=>if(c=='.') return "Game has not completed"))
        return "Draw"
    }

    def main(args: Array[String]):Unit = {
        val T = readLine().toInt
        for(i<-1.to(T)) {
            val arr = List[List[Char]](readLine().toList,readLine().toList,readLine().toList,readLine().toList)
            val empt = readLine()
            println("Case #"+i+": " + solve(arr))
        }
    }
}