8.py

large_number = open("source.txt", 'r').read()
large_number_array = list(map(int, large_number))

def find_max_product(window_size):
    
    if len(large_number_array) < window_size:
        return -1
    
    i = skip_zeros(0, window_size)
    max_product = count_initial_product(i, window_size)

    i += window_size
    window_product = max_product
    while i + window_size <= len(large_number_array):
        next_item = large_number_array[i]
        previous_item = large_number_array[i - window_size]
        if next_item is not 0:
            window_product = window_product // previous_item * next_item
            i += 1
        else:
            i = skip_zeros(i, window_size)
            
            if i + window_size <= len(large_number_array):
                window_product = count_initial_product(i, window_size)
            else:
                break
            i += window_size
        max_product = max(window_product, max_product)
    return max_product


def skip_zeros(i, window_size):
    while 0 in large_number_array[i:i + window_size]:
        zero_index = large_number_array[i:i + window_size].index(0)
        i += zero_index + 1
    return i


def count_initial_product(i, window_size):
    window_product = 1
    for j in range(i, i + window_size):
        window_product *= large_number_array[j]
    return window_product


assert find_max_product(4) == 5832
print(find_max_product(13))