PROGRAM
Palprime Numbers. Palprime numbers are the
palindromic prime numbers i.e., the
prime numbers that are palindrome also.
First palprime number is a 2-digit (2-d) number and it is
11. There is only one palprime, which is 2-digits long.
To generate a 3-digit(3-d) palprime number, there are many
methods. One method is where one just needs to insert a 1-d palprime number in
between 11 and then test for its primeness.
This way only two palprimes are generated(by inserting 3 and
5 between 11)
131 and 151
(insertion of 7 and 11 does not yield a prime number)
You need to write the method GenPalPrime for the
following class that generates palprimes
using the method mentioned here.
public class
PalPrime
{
public static void
GenPalPrime(int n)
{
/*The passed
number n tells the number of digits in the palprime
to be
generated. Acceptable values for n are 2-5*/
}
}
The 5-d palprimes may be generated by inserting some 3-d
palprimes in 11 e.g., insertion of 131,383,797 yields these palprime numbers:
11311, 13831, 17971.
You may define additional methods, if needed.
Sample Input Output:
Enter the width of palprime numbers (ie no of digits in a
palprime no): 2
11
Enter the width of palprime numbers (ie no of digits in a
palprime no): 3
131
151
----------------------------------------------------------------------------------------------------------
/**
* class PalPrime generates palprime numbers.
* @author: Nitendra Verma
* @version: June 11,2013
*/
import java.util.Scanner;
public class PalPrime
{
public static boolean isprime(int n) //method, checks whether a number is prime or not
{
int flag=1;
for(int i=2;i<n;i++)
{
if(n%i==0)
{
flag=0;
break;
}
}
if(flag==1)
return true;
else
return false;
}
public static boolean ispal(int n) //method, checks whether a number is palidrome or not
{
int n1,r1,ntemp,rev=0;
ntemp=n;
do
{
n1=n/10;
r1=n%10;
rev=rev*10+r1;
n=n1;
}
while(n1>0);
if(rev==ntemp)
return true;
else
return false;
}
public static void GenPalPrime(int n) //method to generate numbers which are prime and palindrome both
{
int count=0;
if(n==2)
{
System.out.println("11");
count++;
}
else if(n==3)
{
int begnum=101;
int lnum=0;
boolean boolpr=false;
boolean boolpl=false;
for(int i=3;i<10;i++)
{
boolpr=isprime(i);
boolpl=ispal(i);
if(boolpr==true && boolpl==true)
{
lnum=begnum+i*10;
if(isprime(lnum)==true && ispal(lnum)==true)
{
System.out.println(lnum);
count++;
}
}
}
}
else if(n==4)
{
int begnum=1001;
int lnum=0;
boolean boolpr=false;
boolean boolpl=false;
for(int i=10;i<100;i++)
{
boolpr=isprime(i);
boolpl=ispal(i);
if(boolpr==true && boolpl==true)
{
lnum=begnum+i*10;
if(isprime(lnum)==true && ispal(lnum)==true)
{
System.out.println(lnum);
count++;
}
}
}
}
else if(n==5)
{
int begnum=10001;
int lnum=0;
boolean boolpr=false;
boolean boolpl=false;
for(int i=100;i<1000;i++)
{
boolpr=isprime(i);
boolpl=ispal(i);
if(boolpr==true && boolpl==true)
{
lnum=begnum+i*10;
if(isprime(lnum)==true && ispal(lnum)==true)
{
System.out.println(lnum);
count++;
}
}
}
}
else
System.out.println("Value of n should be within range 2-5");
if(n>=2 && n<=5 && count==0)
System.out.println("No palprime number of this width");
}
public static void main()
{
PalPrime ob=new PalPrime(); //creating object of class PalPrime
Scanner in=new Scanner(System.in); //creating object of class Scanner
System.out.println("Enter the width of palprime numbers(i.e., no of digits in a palprime no):");
int num=in.nextInt();
GenPalPrime(num); //method calling
}
}
OUTPUT
Enter the width of palprime numbers(i.e., no of digits in a palprime no):
3
131
151
/*---------------Program developed by: Nitendra Verma---------------*/
//For more details visit http://javawithnitendra.blogspot.in
