Lecture Notes on 18 Feb 2013

import java.util.*;

public class Test
{
  public static void main (String[] args)
  {
    Scanner sc = new Scanner (System.in);

    /*
    // Prompt the user to enter a number
    System.out.print ("Enter a number: ");

    // Read the number
    int num = sc.nextInt();
    int num_orig = num;

    // Reverse the number
    int revNum = 0;
    while (num > 0)
    {
      revNum = revNum * 10 + (num % 10);
      num = num / 10;
    }

    System.out.println ("Reverse of the number = " + revNum);

    if (revNum == num_orig)
    {
      System.out.println (num_orig + " is palindromic");
    }
    else
    {
      System.out.println (num_orig + " is not palindromic");
    }

    num = num_orig;
    int limit = (int) Math.sqrt (num);
    boolean isPrime = true;
    for (int i = 2; i <= limit; i++)
    {
      if (num % i == 0)
      {
        isPrime = false;
	break;
      }
    }

    if (isPrime)
    {
      System.out.println (num + " is prime");
    }
    else
    {
      System.out.println (num + " is not prime");
    }
    */

    // Print all palindromic primes in a given range
    System.out.print ("Enter low end: ");
    int lo = sc.nextInt();
    System.out.print ("Enter high end: ");
    int hi = sc.nextInt();
    for (int n = lo; n <= hi; n++)
    {
      int limit = (int) Math.sqrt (n);
      boolean isPrime = true;
      for (int i = 2; i <= limit; i++)
      {
        if (n % i == 0)
        {
          isPrime = false;
	  break;
        }
     }
     int n1 = n;
     int n2 = n;
     if (isPrime)
     {
       int revN = 0;
       while (n1 > 0)
       {
         revN = revN * 10 + (n1 % 10);
	 n1 = n1 / 10;
       }
       if (revN == n2)
       {
         System.out.print (n + " ");
       }
     }
    }
    System.out.println ();
  }
}