problem_008_solution_02.py

# https://projecteuler.net/problem=8
# Find the 13 adjacent digits in the 1000-digit number
# that have the greatest product and print the product.


import numpy as np
import time
from functools import wraps

def fn_timer(function):
  @wraps(function)
  def function_timer(*args, **kwargs):
    t0 = time.time()
    result = function(*args, **kwargs)
    t1 = time.time()
    print ("Total time running %s: %s seconds" %
           (function.func_name, str(t1-t0)) )
    return result
  return function_timer

@fn_timer
def find_max():
    NUMBER = """73167176531330624919225119674426574742355349194934\
96983520312774506326239578318016984801869478851843\
85861560789112949495459501737958331952853208805511\
12540698747158523863050715693290963295227443043557\
66896648950445244523161731856403098711121722383113\
62229893423380308135336276614282806444486645238749\
30358907296290491560440772390713810515859307960866\
70172427121883998797908792274921901699720888093776\
65727333001053367881220235421809751254540594752243\
52584907711670556013604839586446706324415722155397\
53697817977846174064955149290862569321978468622482\
83972241375657056057490261407972968652414535100474\
82166370484403199890008895243450658541227588666881\
16427171479924442928230863465674813919123162824586\
17866458359124566529476545682848912883142607690042\
24219022671055626321111109370544217506941658960408\
07198403850962455444362981230987879927244284909188\
84580156166097919133875499200524063689912560717606\
05886116467109405077541002256983155200055935729725\
71636269561882670428252483600823257530420752963450"""

    length = 13
    products = []	# contains product of all 13-adjacent-digit numbers

    while True:
        num = NUMBER[:length]
        # When remaining character is less than 13, stop processing
        if len(num) < length:
            break

        # list(num) converts a string to list of characters
        # map() converts all digit represented as character to real digit
        # np.product() calculate product of all number in the list
        prod = np.product( map( long, list(num) ) )

        # if product equals to 0, dont take it into account
        if prod:
            products.append( prod )
        NUMBER = NUMBER[1:]

    print (max(products))

if __name__ == '__main__':
    find_max()