Happy Number in JAVA

Happy Number

Happy Number: A Happy Number is defined as : Starting with any positive integer, replace the number by the sum of the squares of its digits, and repeat the process until the number equals 1.

Example :-

Input                   : 49

Output                : It is a Happy Number

Input                   : 4

Output                : It is not a Happy Number

Algorithm, Program and Video Link given below :-

Unhappy Number

Happy Number

Algorithm :-

• Input number

• Store the input number in another variable

• Use a infinite for loop

• Inside for loop use While loop to store the sum of square of the digits in a variable

• Check if the number is equal to original number or a particular number repeating after looping.

• If the number is repeating or it is equal to the Input number print “Number is not a Happy Number”

• Otherwise check if the number is equal to 1. If it is equal to 1 then print “It is a Happy Number”

• Else find the sum of the square of the digits again.

• Repeat the process until a desired result is obtained.

• Compile and Run the Program.

  

Program :-

import java.io.*;
import java.util.*;
class Happy_Number
{
    public static void main(String args[])
    {
        Scanner in=new Scanner(System.in);
        int n,p,i,j,k=0,rev,s=0,x;
        int ar[]= new int[100];
        System.out.println("Enter Number");
        n= in.nextInt();// Enter number from user
        p=n; // Store the copy of input number
        for(i=0;;i++)
        {
            while(n>0)
            {
                rev=n%10;
                s=s+(rev*rev);
                n=n/10;
                ar[i]=s;
            }
            for(j=0;j<i;j++)
            {
                if(ar[j]==ar[i])
                {
                    for(x=0;x<=i;x++)
                    {
                        System.out.print(ar[x]+"\t");
                    }
                    System.out.println();
                    System.out.println("It is not a Happy Number : "+p);
                    k=1;
                    break;
                }
            }
            if(k==1)
            {
                break;
            }
            else if(s==1)
            {
                for(x=0;x<=i;x++)
                {
                    System.out.print(ar[x]+"\t");
                }
                System.out.println();
                System.out.println("It is a Happy Number : "+p);
                break;
            }
            else
            {
                n=s;
                s=0;
            }
        } // end of for loop
    } // end of main
} // end of class

 

Output :-

Output

 

Video Link : https://youtu.be/NNDL-PvRaZ0 

 

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