if p < r; mid = Partition(A,p,r) Quicksort(A,p,mid - 1) Quicksort(A,mid + 1,r)

x = A[r] i = p-1 for j = p to r-1 if A[j] ≤ x i = i + 1 exchange A[i] with A[j] exchange A[i+1] with A[r] return i+1