Implementation of Quick Sort in Swift

quickSort.swift

// var numbers: [Int] = [15, 67, 8, 16, 44, 27, 12, 35];
// We will call quicksort with
// quickSort(&numbers, p: 0, r: numbers.count-1);

func quickSort(_ numbers: inout [Int], p: Int, r: Int) -> Void{
  if p<r {
    let q = partition(&numbers, p: p, r: r)
    quickSort(&numbers, p: p, r: q-1);
    quickSort(&numbers, p: q+1, r: r)
  }
}

func partition(_ numbers: inout  [Int],p: Int, r:Int) -> Int{
  let x = numbers[r]
  var i = p - 1;
  for j in p..<r{
    if numbers[j] <= x {
      i = i + 1;
      numbers.swapAt(i, j)
    }
  }
  numbers.swapAt(i+1, r)
  return i+1
}