solve problem 9

Program.cs

@@ -194,8 +194,26 @@ namespace Euler {
       return maxProduct;
     }
 
+    [Fact]
+    static long Problem9() {
+      for (int a = 1; a <= 333; a++) {
+        for (int b = a + 1; b < 1000 - a; b++) {
+          int c = 1000 - b - a;
+          if (c < b) {
+            break;
+          }
+          if (a * a + b * b == c * c) {
+            int result = a * b * c;
+            Assert.Equal(31875000, result);
+            return result;
+          }
+        }
+      }
+      return 0;
+    }
+
     static void Main(string[] args) {
-      WriteLine(Problem8());
+      WriteLine(Problem9());
     }
   }
 }