Kaprekar Number...

A positive whole number 'n' that has 'd' number of digits is squared and split into 2 pieces, a right hand piece that has 'd' digits and a left hand piece that has remaining 'd' or 'd-1' digits. If sum of the pieces is equal to the number then it’s a kaprekar number. The first few Kaprekar numbers are: 9, 45, 297…..

For example 297 is a kaprekar number because:

297² =88209, right hand piece of 88209=209 and left hand piece of 88209=88

Sum=209+88=297 , i.e. equal to the number.

Given the two positive integers p and q, where p < q. Write a program to determine how many kaprekar numbers are there in the range between 'p' and 'q'(both inclusive )and output them.

The input contains two positive integers p and q. Assume p<5000 and q<5000. You are to output the number of kaprekar numbers in the specified range along with their values in the format specified below:

SAMPLE DATA:

INPUT:                  p=1

Q=1000

OUTPUT:     THE KAPREKAR NUMBERS ARE:

1, 9, 45, 55, 99, 297, 999

FREQUENCY OF KAPREKAR NUMBERS IS:8

Solution:-

import java.util.*;

public class Kaprekar

{

    public static void main(String args[])

     {

     Scanner sc=new Scanner(System.in);

         System.out.print("Enter the lower limit:");

         int p=sc.nextInt();

         System.out.print("Enter the upper limit:");

         int q=sc.nextInt();

         if(q<p)

           System.out.println("INVALID INPUT");

           else

            {

                int count=0;

                System.out.println("THE KAPREKAR NUMBERS ARE:-");

                for(int i=p;i<=q;i++) //checking between the limits

                  {

                      String s=""+i;

                      int d=s.length();

                      int sq=i*i;

                      int rd=(int)(sq%(Math.pow(10,d))); //finding right-hand piece

                      int ld=(int)(sq/(Math.pow(10,d))); //finding left-hand piece

                      if(i==(rd+ld))

                       {

                           if(count==0)

                             System.out.print(i);

                             else

                              System.out.print(","+i);

                               count++;

                       }

                    }

                    System.out.println();

                     System.out.println("FREQUENCY OF KAPREKAR NUMBERS IS:"+count);

            }

    }

}