shellSort.py

#shell sort
def shellSort(alist):
    sublistcount = len(alist)//2
    while sublistcount > 0:
        for startposition in range(sublistcount):
            gapInsertionSort(alist, startposition, sublistcount)
        print("After increments of size",sublistcount,"The list is",alist)

        sublistcount = sublistcount // 2

def gapInsertionSort(alist,start,gap):
    for i in range(start+gap,len(alist),gap):
        currentvalue = alist[i]
        position = i

        while position >= gap and alist[position-gap] > currentvalue:
            alist[position] = alist[position-gap]
            position = position-gap

        alist[position] = currentvalue

alist = [54,26,93,17,77,31,44,55,20]
shellSort(alist)
print(alist)