#!/usr/bin/env python
"""
Created on 28 Abr 2017

@author: David Doblas Jiménez
@email: daviddoji@pm.me

Solution for problem 008 of Project Euler
https://projecteuler.net/problem=8
"""

import collections
from itertools import islice

from utils import timeit


# recipe from more-itertools
def sliding_window(iterable, n):
    # sliding_window('ABCDEFG', 4) -> ABCD BCDE CDEF DEFG
    it = iter(iterable)
    window = collections.deque(islice(it, n), maxlen=n)
    if len(window) == n:
        yield tuple(window)
    for x in it:
        window.append(x)
        yield tuple(window)


@timeit("Problem 008")
def compute():
    """
    The four adjacent digits in the 1000-digit number that have the
    greatest product are 9 x 9 x 8 x 9 = 5832.

            731671...963450

    Find the thirteen adjacent digits in the 1000-digit number that have
    the greatest product. What is the value of this product?
    """

    NUM = """
        73167176531330624919225119674426574742355349194934
        96983520312774506326239578318016984801869478851843
        85861560789112949495459501737958331952853208805511
        12540698747158523863050715693290963295227443043557
        66896648950445244523161731856403098711121722383113
        62229893423380308135336276614282806444486645238749
        30358907296290491560440772390713810515859307960866
        70172427121883998797908792274921901699720888093776
        65727333001053367881220235421809751254540594752243
        52584907711670556013604839586446706324415722155397
        53697817977846174064955149290862569321978468622482
        83972241375657056057490261407972968652414535100474
        82166370484403199890008895243450658541227588666881
        16427171479924442928230863465674813919123162824586
        17866458359124566529476545682848912883142607690042
        24219022671055626321111109370544217506941658960408
        07198403850962455444362981230987879927244284909188
        84580156166097919133875499200524063689912560717606
        05886116467109405077541002256983155200055935729725
        71636269561882670428252483600823257530420752963450
        """

    num = NUM.replace("\n", "").replace(" ", "")
    adjacent_digits = 13
    ans = 0
    for nums in sliding_window(num, adjacent_digits):
        prod = 1
        for num in nums:
            prod *= int(num)
        if prod > ans:
            ans = prod

    return ans


if __name__ == "__main__":
    print(f"Result for Problem 008: {compute()}")