Question

Must be written in JAVA Code

Write a program that takes a whole number input from a user and determines whether it’s prime. If the number is not prime, display its unique prime factors. Remember that a prime number’s factors are only 1 and the prime number itself. Every number that’s not prime has a unique prime factorization. For example, consider the number 54. The prime factors of 54 are 2, 3, 3 and 3. When the values are multiplied together, the result is 54. For the number 54, the prime factors output should be 2 and 3. Use Sets as part of your solution.

Answer 1

// do comment if any problem arises

// code

import java.util.*;

class Prime {

    // this function returns true if given number is prime

    public static boolean isPrime(int number) {

        for (int i = 2; i < number; i++) {

            if (number % i == 0)

                return false;

        }

        return true;

    }

    // this function prints prime factors of given numebr

    public static void print_primes(int number) {

        System.out.println("Prime factors of "+number+" are:");

        // create a set

        Set<Integer> factors = new HashSet<Integer>();

        for (int i = 2; i < number; i++) {

            while (number % i == 0) {

                number /= i;

                factors.add(i);

            }

        }

        // print all prime factors in set

        Iterator<Integer> it=factors.iterator();

        while(it.hasNext())

        {

            System.out.print(it.next()+" ");

        }

    }

    public static void main(String[] args) {

        Scanner sc = new Scanner(System.in);

        // read a number from user

        System.out.println("Enter a number: ");

        int number = sc.nextInt();

        if (isPrime(number))

            System.out.println(number + " is a Prime number.");

        else

            print_primes(number);

    }

}

Output: