object Combination{    def combinate(pre:String,m: Int,data: String){     data.foreach{ e =>       if(pre.length() == m-1){          if(!pre.contains(e))            println(pre+e)       }else{         if(!pre.contains(e))           combinate(pre+e,m,data)       }     }  }    def arrange(pre:String,m:Int,data:String){    data.foreach{      e =>        if(pre.length() == m-1)          println(pre+e)        else          arrange(pre+e,m,data)    }  }    def main(args: Array[String]){//    combinate("",3,"abc")    arrange("",2,"abc")  }}