def partition(a, start, end):
pivot = a[end]
i = start - 1 # ix of the last element in "left", initially outside the list
for j in range(start, end):
if a[j] <= pivot:
i += 1
swap(a, i, j)
swap(a, i + 1, end)
return i + 1 # position of the pivot, "start" of next iterations
def reverse(array):
length = len(array)
mid = math.floor(length / 2)
# swap elements on either side of the midpoint
ix = 0
while ix < mid:
swap(array, ix, length - ix - 1)
ix += 1
return array
def insert_in_sorted_order(array, el):
# replace the empty spot with the element
array[-1] = el
# swap backwards until element is in the right place
cur = len(array) - 1 # index of the element to insert
ix = cur - 1 # start a second-to-last
while ix >= 0 and array[ix] > array[cur]:
swap(array, ix, cur)
cur = ix
ix -= 1
return array
