Algorithm inPlaceQuickSort(S,a, B ) :
  Input: Sequence S of distinct elements; integers a and b
  Output: Sequence S with elements originally from ranks from a to b, inclusive,
    sorted in nondecreasing order from ranks a to b
  if a ? b then return        {empty subrange}
  p ? S.elemAtRank(B)       {pivot}
  l ? a       {will scan rightward}
  r ? b? 1  {will scan leftward}
  while l ? r do
    {find an element larger than the pivot}
    while l ? r and S.elemAtRank(l)? p do
     l ? l + 1
    {find an element smaller than the pivot}
    while r ? l and S.elemAtRank® ? p do
     r ? r ? 1
    if l < r then
       S.swapElements(S.atRank(l),S.atRank®)
  {put the pivot into its final place}
  S.swapElements(S.atRank(l),S.atRank(B))
  {recursive calls}
  inPlaceQuickSort(S,a,l ? 1)
  inPlaceQuickSort(S,l + 1,B)