Initial data commit

Task/Happy-numbers/C-sharp/happy-numbers-1.cs

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+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+
+namespace HappyNums
+{
+    class Program
+    {
+        public static bool ishappy(int n)
+        {
+            List<int> cache = new List<int>();
+            int sum = 0;
+            while (n != 1)
+            {
+                if (cache.Contains(n))
+                {
+                    return false;
+                }
+                cache.Add(n);
+                while (n != 0)
+                {
+                    int digit = n % 10;
+                    sum += digit * digit;
+                    n /= 10;
+                }
+                n = sum;
+                sum = 0;
+            }
+           return true;
+        }
+
+        static void Main(string[] args)
+        {
+            int num = 1;
+            List<int> happynums = new List<int>();
+
+            while (happynums.Count < 8)
+            {
+                if (ishappy(num))
+                {
+                    happynums.Add(num);
+                }
+                num++;
+            }
+            Console.WriteLine("First 8 happy numbers : " + string.Join(",", happynums));
+        }
+    }
+}

Task/Happy-numbers/C-sharp/happy-numbers-2.cs

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+using System;
+using System.Collections.Generic;
+class Program
+{
+
+    static int[] sq = { 1, 4, 9, 16, 25, 36, 49, 64, 81 };
+
+    static bool isOne(int x)
+    {
+        while (true)
+        {
+            if (x == 89) return false;
+            int s = 0, t;
+            do if ((t = (x % 10) - 1) >= 0) s += sq[t]; while ((x /= 10) > 0);
+            if (s == 1) return true;
+            x = s;
+        }
+    }
+
+    static void Main(string[] args)
+    {
+        const int Max = 10_000_000; DateTime st = DateTime.Now;
+        Console.Write("---Happy Numbers---\nThe first 8:");
+        int c = 0, i; for (i = 1; c < 8; i++)
+            if (isOne(i)) Console.Write("{0} {1}", c == 0 ? "" : ",", i, ++c);
+        for (int m = 10; m <= Max; m *= 10)
+        {
+            Console.Write("\nThe {0:n0}th: ", m);
+            for (; c < m; i++) if (isOne(i)) c++;
+            Console.Write("{0:n0}", i - 1);
+        }
+        Console.WriteLine("\nComputation time {0} seconds.", (DateTime.Now - st).TotalSeconds);
+    }
+}