C# Implementation of Problem 8

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class p0008
: Euler.IEuler
object Answer ()
 1/*
 2Project Euler Problem 8
 3
 4In Python I did this with an iterator, but that is more cumbersome here,
 5so I just did it with a loop that slices.
 6
 7Problem:
 8
 9The four adjacent digits in the 1000-digit number that have the greatest
10product are 9 × 9 × 8 × 9 = 5832.
11
1273167176531330624919225119674426574742355349194934
1396983520312774506326239578318016984801869478851843
1485861560789112949495459501737958331952853208805511
1512540698747158523863050715693290963295227443043557
1666896648950445244523161731856403098711121722383113
1762229893423380308135336276614282806444486645238749
1830358907296290491560440772390713810515859307960866
1970172427121883998797908792274921901699720888093776
2065727333001053367881220235421809751254540594752243
2152584907711670556013604839586446706324415722155397
2253697817977846174064955149290862569321978468622482
2383972241375657056057490261407972968652414535100474
2482166370484403199890008895243450658541227588666881
2516427171479924442928230863465674813919123162824586
2617866458359124566529476545682848912883142607690042
2724219022671055626321111109370544217506941658960408
2807198403850962455444362981230987879927244284909188
2984580156166097919133875499200524063689912560717606
3005886116467109405077541002256983155200055935729725
3171636269561882670428252483600823257530420752963450
32
33Find the thirteen adjacent digits in the 1000-digit number that have the
34greatest product. What is the value of this product?
35*/
36using System;
37
38namespace Euler
39{
40    public class p0008 : IEuler
41    {
42        public object Answer()
43        {
44            String str = String.Concat(
45                "73167176531330624919225119674426574742355349194934",
46                "96983520312774506326239578318016984801869478851843",
47                "85861560789112949495459501737958331952853208805511",
48                "12540698747158523863050715693290963295227443043557",
49                "66896648950445244523161731856403098711121722383113",
50                "62229893423380308135336276614282806444486645238749",
51                "30358907296290491560440772390713810515859307960866",
52                "70172427121883998797908792274921901699720888093776",
53                "65727333001053367881220235421809751254540594752243",
54                "52584907711670556013604839586446706324415722155397",
55                "53697817977846174064955149290862569321978468622482",
56                "83972241375657056057490261407972968652414535100474",
57                "82166370484403199890008895243450658541227588666881",
58                "16427171479924442928230863465674813919123162824586",
59                "17866458359124566529476545682848912883142607690042",
60                "24219022671055626321111109370544217506941658960408",
61                "07198403850962455444362981230987879927244284909188",
62                "84580156166097919133875499200524063689912560717606",
63                "05886116467109405077541002256983155200055935729725",
64                "71636269561882670428252483600823257530420752963450"
65            );
66            long answer = 0;
67            for (int i = 0; i < str.Length - 13; i++)
68            {
69                long prod = 1;
70                foreach (char c in str.Substring(i, 13))
71                    prod *= (long)c - '0';
72
73                if (prod > answer)
74                    answer = prod;
75            }
76            return answer;
77        }
78    }
79}