Michael Sjöberg

# Largest product in a series
#
# The four adjacent digits in the 1000-digit number that 
# have the greatest product are 9 × 9 × 8 × 9 = 5832.
#
# 73167176531330624919225119674426574742355349194934
# 96983520312774506326239578318016984801869478851843
# 85861560789112949495459501737958331952853208805511
# 12540698747158523863050715693290963295227443043557
# 66896648950445244523161731856403098711121722383113
# 62229893423380308135336276614282806444486645238749
# 30358907296290491560440772390713810515859307960866
# 70172427121883998797908792274921901699720888093776
# 65727333001053367881220235421809751254540594752243
# 52584907711670556013604839586446706324415722155397
# 53697817977846174064955149290862569321978468622482
# 83972241375657056057490261407972968652414535100474
# 82166370484403199890008895243450658541227588666881
# 16427171479924442928230863465674813919123162824586
# 17866458359124566529476545682848912883142607690042
# 24219022671055626321111109370544217506941658960408
# 07198403850962455444362981230987879927244284909188
# 84580156166097919133875499200524063689912560717606
# 05886116467109405077541002256983155200055935729725
# 71636269561882670428252483600823257530420752963450
#
# Find the thirteen adjacent digits in the 1000-digit 
# number that have the greatest product. What is the
# value of this product?
#
# https://projecteuler.net/problem=8

import numpy as np

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

nlist = list(''.join(str.strip().split('\n')))
nlist = list(map(int, nlist))

# test
adj_digits = 4
max_product = 0
for i in range(len(nlist)):
    if (i + adj_digits > len(nlist)):
        break
    product = np.prod(nlist[i:i+adj_digits])
    if product > max_product:
        max_product = product

assert(max_product == 5832)

# solution
adj_digits = 13
max_product = 0
for i in range(len(nlist)):
    if (i + adj_digits > len(nlist)):
        break
    product = np.prod(nlist[i:i+adj_digits])
    if product > max_product:
        max_product = product

print(max_product)
# 23514624000