project-euler/largest_product_in_a_series.py

import re
from functools import reduce

'''
The four adjacent digits in the 1000-digit number that have the greatest product are 9 × 9 × 8 × 9 = 5832. Find the thirteen adjacent digits in the 1000-digit number that have the greatest product. What is the value of this product?
'''

num_str = '''7316717653133062491922511967442657474235534919493496983520312774506326239578318016984801869478851843858615607891129494954595017379583319528532088055111254069874715852386305071569329096329522744304355766896648950445244523161731856403098711121722383113622298934233803081353362766142828064444866452387493035890729629049156044077239071381051585930796086670172427121883998797908792274921901699720888093776657273330010533678812202354218097512545405947522435258490771167055601360483958644670632441572215539753697817977846174064955149290862569321978468622482839722413756570560574902614079729686524145351004748216637048440319989000889524345065854122758866688116427171479924442928230863465674813919123162824586178664583591245665294765456828489128831426076900422421902267105562632111110937054421750694165896040807198403850962455444362981230987879927244284909188845801561660979191338754992005240636899125607176060588611646710940507754100225698315520005593572972571636269561882670428252483600823257530420752963450'''

def find_greatest_product_in_series(num_str):
    num_list = re.split('', num_str)[1:-1]
    greatest_product = 0
    for i in range( len(num_list) ):
        try:
            thirteen_digits = num_list[i:i + 13]
            if len(thirteen_digits) == 13:
                product = reduce(
                    (lambda x, y: int(x) * int(y)), thirteen_digits)
                if product > greatest_product:
                    greatest_product = product
                else:
                    continue
            else:
                continue
        except IndexError:
            continue
    return greatest_product