From 09ddcab5a4c433014137b60d370ac1e25d45d076 Mon Sep 17 00:00:00 2001
From: Colin McMillen <colin@semicolin.games>
Date: Wed, 18 Nov 2020 18:13:51 -0500
Subject: [PATCH] solve problem 8

---
 Program.cs | 41 ++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 40 insertions(+), 1 deletion(-)

diff --git a/Program.cs b/Program.cs
index 0c6bc22..1c6a726 100644
--- a/Program.cs
+++ b/Program.cs
@@ -155,8 +155,47 @@ namespace Euler {
   		return result;
   	}
 
+    [Fact]
+    static long Problem8() {
+      string number =
+          "73167176531330624919225119674426574742355349194934" +
+          "96983520312774506326239578318016984801869478851843" +
+          "85861560789112949495459501737958331952853208805511" +
+          "12540698747158523863050715693290963295227443043557" +
+          "66896648950445244523161731856403098711121722383113" +
+          "62229893423380308135336276614282806444486645238749" +
+          "30358907296290491560440772390713810515859307960866" +
+          "70172427121883998797908792274921901699720888093776" +
+          "65727333001053367881220235421809751254540594752243" +
+          "52584907711670556013604839586446706324415722155397" +
+          "53697817977846174064955149290862569321978468622482" +
+          "83972241375657056057490261407972968652414535100474" +
+          "82166370484403199890008895243450658541227588666881" +
+          "16427171479924442928230863465674813919123162824586" +
+          "17866458359124566529476545682848912883142607690042" +
+          "24219022671055626321111109370544217506941658960408" +
+          "07198403850962455444362981230987879927244284909188" +
+          "84580156166097919133875499200524063689912560717606" +
+          "05886116467109405077541002256983155200055935729725" +
+          "71636269561882670428252483600823257530420752963450";
+      int numDigits = 13;
+      long maxProduct = 0;
+      for (int i = 0; i < number.Length - numDigits; i++) {
+        long product = 1;
+        for (int j = i; j < i + numDigits; j++) {
+          int digit = Int32.Parse(number.Substring(j, 1));
+          product *= digit;
+        }
+        if (product > maxProduct) {
+          maxProduct = product;
+        }
+      }
+      Assert.Equal(23514624000, maxProduct);
+      return maxProduct;
+    }
+
     static void Main(string[] args) {
-      WriteLine(Problem7());
+      WriteLine(Problem8());
     }
   }
 }