Need help in solving the special string Again problem "the scala way"

hey all,
thanks for the posts.
it was not homework, I was just trying out some problems online and learn scala bit by bit.
my solution was very bad and time issues arises so wanted to know a better one also if scala has a better way of solving it.



    // Complete the substrCount function below.
    def substrCount(n: Int, s: String): Long = {

    var result =s.size
    val arr= s.toCharArray
    var myList = List[String]()
     def isValid(m:String):Unit ={
        var setval=m.split("").toSet
        if (setval.size <=2){
            var v_strArr=m.toCharArray
            if(v_strArr(0)==v_strArr(v_strArr.size-1) && (m.size%2) !=0 && setval.size>1)
                myList :+= m
            if(setval.size==1)
                myList :+= m
        }
      }

  for(x<-0 until n){
    
    for(y<- x+1 until n){
      if(arr(x)==arr(y))
      {  
      isValid(s.substring(x,y+1)) }
    }
    
  }
  println(myList)
  result +=myList.size
  println(result)
  result
    


    }

    def main(args: Array[String]) {
        val stdin = scala.io.StdIn

        val printWriter = new PrintWriter(sys.env("OUTPUT_PATH"))

        val n = stdin.readLine.trim.toInt

        val s = stdin.readLine

        val result = substrCount(n, s)

        printWriter.println(result)

        printWriter.close()
    }