Python Implementation of Problem 8

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Includes

Problem Solution

Project Euler Problem 8

The biggest problem with this was remembering how to do groupwise()

Revision 1:

Correctly specify type on groupwise

Revision 2:

Have a __future__ import to get new generator behavior; no noticable change in performance

Problem:

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?

python.src.p0008.main() → int
 1"""
 2Project Euler Problem 8
 3
 4The biggest problem with this was remembering how to do groupwise()
 5
 6Revision 1:
 7
 8Correctly specify type on groupwise
 9
10Revision 2:
11
12Have a __future__ import to get new generator behavior; no noticable change in
13performance
14
15Problem:
16
17The four adjacent digits in the 1000-digit number that have the greatest
18product are 9 × 9 × 8 × 9 = 5832.
19
2073167176531330624919225119674426574742355349194934
2196983520312774506326239578318016984801869478851843
2285861560789112949495459501737958331952853208805511
2312540698747158523863050715693290963295227443043557
2466896648950445244523161731856403098711121722383113
2562229893423380308135336276614282806444486645238749
2630358907296290491560440772390713810515859307960866
2770172427121883998797908792274921901699720888093776
2865727333001053367881220235421809751254540594752243
2952584907711670556013604839586446706324415722155397
3053697817977846174064955149290862569321978468622482
3183972241375657056057490261407972968652414535100474
3282166370484403199890008895243450658541227588666881
3316427171479924442928230863465674813919123162824586
3417866458359124566529476545682848912883142607690042
3524219022671055626321111109370544217506941658960408
3607198403850962455444362981230987879927244284909188
3784580156166097919133875499200524063689912560717606
3805886116467109405077541002256983155200055935729725
3971636269561882670428252483600823257530420752963450
40
41Find the thirteen adjacent digits in the 1000-digit number that have the
42greatest product. What is the value of this product?
43"""
44from functools import reduce
45from operator import mul
46
47from .lib.iters import groupwise
48
49
50def main() -> int:
51    string = ("73167176531330624919225119674426574742355349194934"
52              "96983520312774506326239578318016984801869478851843"
53              "85861560789112949495459501737958331952853208805511"
54              "12540698747158523863050715693290963295227443043557"
55              "66896648950445244523161731856403098711121722383113"
56              "62229893423380308135336276614282806444486645238749"
57              "30358907296290491560440772390713810515859307960866"
58              "70172427121883998797908792274921901699720888093776"
59              "65727333001053367881220235421809751254540594752243"
60              "52584907711670556013604839586446706324415722155397"
61              "53697817977846174064955149290862569321978468622482"
62              "83972241375657056057490261407972968652414535100474"
63              "82166370484403199890008895243450658541227588666881"
64              "16427171479924442928230863465674813919123162824586"
65              "17866458359124566529476545682848912883142607690042"
66              "24219022671055626321111109370544217506941658960408"
67              "07198403850962455444362981230987879927244284909188"
68              "84580156166097919133875499200524063689912560717606"
69              "05886116467109405077541002256983155200055935729725"
70              "71636269561882670428252483600823257530420752963450")
71    digits = [int(x) for x in string]
72    answer = 0
73    for operands in groupwise(digits, 13):
74        num = reduce(mul, operands, 1)
75        answer = max(answer, num)
76    return answer