Initial data commit

Task/Digital-root-Multiplicative-digital-root/C-sharp/digital-root-multiplicative-digital-root.cs

@@ -0,0 +1,39 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+
+class Program
+{
+    static Tuple<int, int> DigitalRoot(long num)
+    {
+        int mp = 0;
+        while (num > 9)
+        {
+            num = num.ToString().ToCharArray().Select(x => x - '0').Aggregate((a, b) => a * b);
+            mp++;
+        }
+        return new Tuple<int, int>(mp, (int)num);
+    }
+    static void Main(string[] args)
+    {
+        foreach (long num in new long[] { 123321, 7739, 893, 899998 })
+        {
+            var t = DigitalRoot(num);
+            Console.WriteLine("{0} has multiplicative persistence {1} and multiplicative digital root {2}", num, t.Item1, t.Item2);
+        }
+
+        const int twidth = 5;
+        List<long>[] table = new List<long>[10];
+        for (int i = 0; i < 10; i++)
+            table[i] = new List<long>();
+        long number = -1;
+        while (table.Any(x => x.Count < twidth))
+        {
+            var t = DigitalRoot(++number);
+            if (table[t.Item2].Count < twidth)
+                table[t.Item2].Add(number);
+        }
+        for (int i = 0; i < 10; i++)
+            Console.WriteLine(" {0} : [{1}]", i, string.Join(", ", table[i]));
+    }
+}