"```python
lst = [i for i in range(20, 0, -1)]
length = len(lst)
r = length // 2
while r:
for i in range(length - r):
if lst[i] > lst[i + r]:
lst[i], lst[i + r] = lst[i + r], lst[i]
r = r // 2
else:
for i in range(length - 1):
for i in range(i, -1, -1):
if lst[i] > lst[i + 1]:
lst[i], lst[i + 1] = lst[i + 1], lst[i]
"