scala31. ``` object scala3 { def main(args: Array[String]):

object scala3 {
  def main(args: Array[String]): Unit = {
    val arr = Array(1,2,3,4)
    val rst = arr.fold(10)( (x,y) => x - y)
    println(s"rst =${rst}")
  }
}

object scala4 {
  def main(args: Array[String]): Unit = {
    Array(-1,20,-100,3,40).sorted.foreach(println)
    Array("zip","bus","apple","banana","card").sorted.foreach(println)
  }
}

object scala5 {
  def main(args: Array[String]): Unit = {
    Array(-1,2,0,4,9).sortWith((x,y)=> Math.abs(x - 0) < Math.abs(y-0)).foreach(println)
  }
}