// map of strings
object Main extends App
{
  val myList = List("abc", "bcd", "cde", "def", "efg", "ebat", "ahuet", "blya")

  val w = myList.foldLeft(Map[Char, List[String]]()) {(acc : Map[Char, List[String]], s: String) =>
    if (!(acc contains s.head)) {acc + (s.head -> List(s))}
    else {acc - s.head + (s.head -> (s :: acc(s.head)))}}

  print(w)
}