input.in

car truck 8 4 bus 6 1

Sort.scala

object Sort {
  def main(args: Array[String]){
    def merge(ints: List[String], strings: List[String], line: List[String])(isInt: String => Boolean): List[String] = (ints, strings) match{
      case (ints, Nil) => ints
      case (Nil, strings) => strings
      case (i :: iTails, s :: sTails) =>
        if(isInt(line.head)) i :: merge(iTails, strings, line.tail)(isInt)
        else s :: merge(ints, sTails, line.tail)(isInt)
    }
    val toCells = (_: String).trim.split(" +").toList
    val isInt = (_:String).matches("""\d+""")
    io.Source.stdin.getLines.map(toCells).foreach{ line =>
      val (ints, strings) = line.partition(isInt(_))
      println(merge(ints.sortWith(_<_), strings.sortWith(_<_), line)(isInt).mkString(", "))
    }
  }
}