using System;

using System.Collections.Generic;

using System.Linq;

​

public class Program

{

    public static void Main()

    {

        Console.WriteLine(IsHappy(3));

    }

​

    public static bool IsHappy(int n)

    {

        var hashSet = new HashSet<int>();

        var currentSum = n;

        while (currentSum != 1)

        {

            if (hashSet.Contains(currentSum))

                return false;

            hashSet.Add(currentSum);

            var activeSum = 0;

            var currentSumArr = currentSum.ToString().Select(n => Convert.ToInt32(n.ToString())).ToArray();

            for (int i = 0; i < currentSumArr.Length; i++)

            {

                Console.WriteLine("values multiplied {0}", (currentSumArr[i] * currentSumArr[i]));

                activeSum += (currentSumArr[i] * currentSumArr[i]);

            }

​

            currentSum = activeSum;

            Console.WriteLine(activeSum);

        }

​

        return true;

    }

}