ShellSort.py

def shell_sort(a_sort):
    sublist_count = len(a_list) // 2
    while sublist_count > 0:
        for start_position in range(sublist_count):
            gap_insertion_sort(a_list, start_position, sublist_count)
        
        print("After increments of size ", sublist_count, "The list is ", a_list)

        sublist_count = sublist_count // 2
def gap_insertion_sort(a_list, start, gap):
    for i in range(start+gap, len(a_list), gap):
        current_value = a_list[i]
        position = i
        while position >= gap and a_list[position-gap]>current_value:
            a_list[position] = a_list[position-gap]
            position = position - gap
        a_list[position] = current_value

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