Quick Sort in Scala.

QuickSort.scala

def quickSortRecursive(list: Array[Int])(low: Int=0, high: Int=list.length-1): Unit = {
  if (low<high) {
    swap(list,Random.nextInt(high),high)
    val pivot = partition(list, low, high)
    quickSortRecursive(list)(low, pivot-1)
    quickSortRecursive(list)(pivot+1, high)
  }
}

private def partition(list: Array[Int], low: Int, high: Int): Int = {
  val pivot = list(high)
  var lowhigh = low
  for (i <- low until high) {
    if (list(i) < pivot) {
      swap(list, lowhigh, i);
      lowhigh += 1;
    }	
  }
  swap(list, lowhigh, high);
  lowhigh
}

private def swap(list: Array[Int], i: Int, j: Int): Unit = {
  val tmp = list(i)
  list(i) = list(j)
  list(j) = tmp
}