//AMEN-AMEN, MA. SARAH

//VILLABROZA, HANSSELL D.

//CCP 1103 - ITDC

//HAPPY NUMBERS

​

using System;                    

public class Program 

{  

    public static void Main(string[] args)

    {

            string answer;

​

            do

            {

                string inputNumber;

                int sum;

                int firstDigit;

                int secondDigit;

                int thirdDigit;

                int fourthDigit;

                int fifthDigit;

                int number;

​

                Console.Clear();

                Console.WriteLine("Happy Numbers");

                Console.WriteLine();

​

                Console.Write("Enter a number: ");

                inputNumber = Console.ReadLine();

                if (Int32.TryParse(inputNumber, out number) == true)

                {

                    if (number <= 0)

                    {

                        Console.WriteLine("Zero or negative input is not allowed.");

                    }

                    else if (number > 20000)

                    {

                        Console.WriteLine("Invalid input. Please input 1-20,000 only.");

                    }

                    else

                    {

                        for (int i = 0; i <= 50; i++)

                        {

                            if (number < 10 && number != 1)

                            {

                                sum = number * number;

                                number = sum;

                            }

                            else if (number >= 10 && number < 100)

                            {

                                firstDigit = number % 10;

                                secondDigit = number / 10;

                                sum = (firstDigit * firstDigit) + (secondDigit * secondDigit);

                                number = sum;

                            }

                            else if (number >= 100 && number < 1000)

                            { 

                                thirdDigit = number / 100;

                                secondDigit = (number / 10) - (thirdDigit * 10);

                                firstDigit = number - (thirdDigit * 100) - (secondDigit * 10);

                                sum = (firstDigit * firstDigit) + (secondDigit * secondDigit) + (thirdDigit * thirdDigit);

                                number = sum;

                            }

                            else if (number >= 1000 && number < 10000)

                            {

                                firstDigit = number % 10;

                                number = number / 10;

                                secondDigit = number % 10;

                                number = number / 10;

                                thirdDigit = number % 10;

                                number = number / 10;

                                fourthDigit = number % 10;

                                sum = (firstDigit * firstDigit) + (secondDigit * secondDigit) + (thirdDigit * thirdDigit) + (fourthDigit * fourthDigit);

                                number = sum;

                            }

                            else if (number >= 1000 && number < 10000)

                            {

                                firstDigit = number % 10;

                                number = number / 10;

                                secondDigit = number % 10;

                                number = number / 10;

                                thirdDigit = number % 10;

                                number = number / 10;

                                fourthDigit = number % 10;

                                sum = (firstDigit * firstDigit) + (secondDigit * secondDigit) + (thirdDigit * thirdDigit) + (fourthDigit * fourthDigit);

                                number = sum;

                            }

                            else if (number >= 1-000 && number < 100000)

                            {

                                firstDigit = number % 10;

                                number = number / 10;

                                secondDigit = number % 10;

                                number = number / 10;

                                thirdDigit = number % 10;

                                number = number / 10;

                                fourthDigit = number % 10;

                                number = number / 10;

                                fifthDigit = number % 10;

                                sum = (firstDigit * firstDigit) + (secondDigit * secondDigit) + (thirdDigit * thirdDigit) + (fourthDigit * fourthDigit) + (fifthDigit * fifthDigit);

                                number = sum;

                            }

                            else

                            {

                                number = 1;

                                i = 51;

                            }

                        }

                        if (number == 1)

                        {

                            Console.WriteLine(inputNumber + " is a happy number.");

                        }

                        else

                        {

                            Console.WriteLine(inputNumber + " is not a happy number.");

                        }

                    }

                }

                else

                {

                    Console.WriteLine("Invalid Input. Please Enter a numeric value.");

                }

​

                Console.WriteLine();

                Console.Write("Do you want to try again [Y/y]? ");

                answer = Console.ReadLine();

​

            } while ((answer == "Y") || (answer == "y"));

​

            Console.WriteLine("End of the program. Press any key to exit...");

     }

}