# Author: OMKAR PATHAK

# This program illustrates the shell sort implementation in Python

# According to Wikipedia "Shell sort or Shell's method, is an in-place comparison sort.

# It can be seen as either a generalization of sorting by exchange (bubble sort) or sorting by

# insertion (insertion sort). The method starts by sorting pairs of elements far apart from each other,

# then progressively reducing the gap between elements to be compared. Starting with far apart elements

# can move some out-of-place elements into position faster than a simple nearest neighbor exchange."

# Best Case O(n logn); Average Case O(depends on gap sequence); Worst Case O(n)

def shellSort(myList):

gap = len(myList) // 2

while gap > 0:

for i in range(gap, len(myList)):

currentItem = myList[i]

j = i

while j >= gap and myList[j - gap] > currentItem:

myList[j] = myList[j - gap]

j -= gap

myList[j] = currentItem

gap //= 2

return myList

if __name__ == '__main__':

myList = [12, 23, 4, 5, 3, 2, 12, 81, 56, 95]

print(shellSort(myList))