[Question 1] ISC 2016 Computer Practical Paper Solved - Circular Prime

17 February 2016

Solution of Program 1 of ISC 2016 Computer Science Paper 2 (Practical) Exam. Java program to input a number and check whether it is a Circular Prime or not.

Click here to download the complete ISC 2016 Computer Science Paper 2 (Practical).

Question:

A Circular Prime is a prime number that remains prime under cyclic shifts of its digits. When the leftmost digit is removed and replaced at the end of the remaining string of digits, the generated number is still prime. The process is repeated until the original number is reached again. A number is said to be prime if it has only two factors I and itself.

Example: 131 311 113 Hence, 131 is a circular prime.

Test your program with the sample data and some random data: Example 1 INPUT :N = 197 OUTPUT: 197 971 719 197 IS A CIRCULAR PRIME Example 2 INPUT :N = 1193 OUTPUT: 1193 1931 9311 3119 1193 IS A CIRCULAR PRIME Example 3 INPUT :N = 29 OUTPUT: 29 92 29 IS NOT A CIRCULAR PRIME

Programming Code:

Java

/**
* The class CircularPrime_Q1_ISC2016 inputs a number and
* checks whether it is a Circular Prime or not
* @author : www.guideforschool.com
* @Program Type : BlueJ Program - Java
* @Question Year : ISC Practical 2016 Question 1
*/

import java.util.*;
class CircularPrime_Q1_ISC2016
{
    boolean isPrime(int n) // Function for checking whether a number is prime or not
    {
        int c = 0;
        for(int i = 1; i<=n; i++)
        {
            if(n%i == 0)
                c++;
        }
        if(c == 2)
            return true;
        else
            return false;
    }
    
    int circulate(int n) //Function for circulating the digits to form new number
    {
        String s = Integer.toString(n);
        String p = s.substring(1)+s.charAt(0);
        int a = Integer.parseInt(p);
        return a;
    }
    
    void isCircularPrime(int n) //Function to check for circular prime
    {
        int f = 0,a = n;
        do
        {
            System.out.println(a);
            if(isPrime(a)==false)
            {
                f = 1;
            }
            a = circulate(a);
        }while(a!=n);
        
        if(f==1)
            System.out.println(n+" IS NOT A CIRCULAR PRIME");
        else
            System.out.println(n+" IS A CIRCULAR PRIME");
    }
    
    public static void main(String args[])
    {
        CircularPrime_Q1_ISC2016 ob = new CircularPrime_Q1_ISC2016();
        Scanner sc = new Scanner(System.in);
        System.out.print("Enter a number : ");
        int n = sc.nextInt();
        ob.isCircularPrime(n);
    }
}

Output:

Enter a number : 87 87 87 IS NOT A CIRCULAR PRIME

Enter a number : 1193 1193 1931 9311 3119 1193 IS A CIRCULAR PRIME

Enter a number : 123 123 231 312 123 IS NOT A CIRCULAR PRIME