Check whether a number is semiprime or not

Given a positive integer n. Find whether a number is a semiprime or not. Print True if number is semiprime else False. A semiprime is a natural number that is a product of two prime numbers.

Examples :

Input: 6
Output: True
Explanation
6 is a semiprime number as it is a
product of two prime numbers 2 and 3.

Input: 9
Output: True

Input: 8
Output: False

The approach is simple, factorize the given number by dividing it with the divisor of a number to remove the composite number. Meanwhile keep updating the count variable of prime number.

C

filter_none

edit
close

play_arrow

link
brightness_4
code

// C Program to check whether
// number is semiprime or not
#include <stdio.h>
  
// Utility function to check whether
// number is semiprime or not
int checkSemiprime(int num)
{
    int cnt = 0;
  
    for (int i = 2; cnt < 2 && i * i <= num; ++i)
        while (num % i == 0)
            num /= i, ++cnt; // Increment count
                             // of prime numbers
  
    // If number is greater than 1, add it to
    // the count variable as it indicates the
    // number remain is prime number
    if (num > 1)
        ++cnt;
  
    // Return '1' if count is equal to '2' else
    // return '0'
    return cnt == 2;
}
  
// Function to print 'True' or 'False'
// according to condition of semiprime
void semiprime(int n)
{
    if (checkSemiprime(n))
        printf("True\n");
    else
        printf("False\n");
}
  
// Driver code
int main()
{
    int n = 6;
    semiprime(n);
  
    n = 8;
    semiprime(n);
    return 0;
}

chevron_right


Java

filter_none

edit
close

play_arrow

link
brightness_4
code

// Java Program to check whether
// number is semiprime or not
class GFG{
      
    // Utility function to check whether
    // number is semiprime or not
    static int checkSemiprime(int num)
    {
        int cnt = 0;
      
        for (int i = 2; cnt < 2 && 
                     i * i <= num; ++i)
                       
            while (num % i == 0){
                num /= i;
                  
                // Increment count
                // of prime numbers
                ++cnt;
                }
      
        // If number is greater than 1, 
        // add it to the count variable 
        // as it indicates the number 
        // remain is prime number
        if (num > 1)
            ++cnt;
      
        // Return '1' if count is equal 
        // to '2' else return '0'
        return cnt == 2 ? 1 : 0;
    }
      
    // Function to print 'True' or 'False'
    // according to condition of semiprime
    static void semiprime(int n)
    {
        if (checkSemiprime(n) != 0)
            System.out.printf("True\n");
        else
            System.out.printf("False\n");
    }
      
    // Driver code
    public static void main(String[] args)
    {
        int n = 6;
        semiprime(n);
      
        n = 8;
        semiprime(n);
    }
}
  
// This code is contributed by
// Smitha Dinesh Semwal

chevron_right


Python3

filter_none

edit
close

play_arrow

link
brightness_4
code

# Python Program to check whether
# number is semiprime or not
import math
# Utility function to check whether
# number is semiprime or not
def checkSemiprime(num):
    cnt = 0
  
    for i in range(2, int(math.sqrt(num)) + 1):
        while num % i == 0:
            num /= i
            cnt += 1 # Increment count
                    # of prime number
  
        # If count is greater than 2,
        # break loop 
        if cnt >= 2
            break
    # If number is greater than 1, add it to
    # the count variable as it indicates the
    # number remain is prime number
    if(num > 1):
        cnt += 1
  
    # Return '1' if count is equal to '2' else
    # return '0'
    return cnt == 2
  
# Function to print 'True' or 'False'
# according to condition of semiprime
def semiprime(n):
    if checkSemiprime(n) == True:
        print("True")
    else:
        print("False")
  
# Driver code
n = 6
semiprime(n)
  
n = 8
semiprime(n);

chevron_right


C#

filter_none

edit
close

play_arrow

link
brightness_4
code

// C# Program to check whether
// number is semiprime or not
using System;
class GFG{
      
    // Utility function to check whether
    // number is semiprime or not
    static int checkSemiprime(int num)
    {
        int cnt = 0;
      
        for (int i = 2; cnt < 2 && 
                    i * i <= num; ++i)
                      
            while (num % i == 0){
                num /= i;
                  
                // Increment count
                // of prime numbers
                ++cnt;
                }
      
        // If number is greater than 1, 
        // add it to the count variable 
        // as it indicates the number 
        // remain is prime number
        if (num > 1)
            ++cnt;
      
        // Return '1' if count is equal 
        // to '2' else return '0'
        return cnt == 2 ? 1 : 0;
    }
      
    // Function to print 'True' or 'False'
    // according to condition of semiprime
    static void semiprime(int n)
    {
        if (checkSemiprime(n) != 0)
            Console.WriteLine("True");
        else
            Console.WriteLine("False");
    }
      
    // Driver code
    public static void Main()
    {
        int n = 6;
        semiprime(n);
      
        n = 8;
        semiprime(n);
    }
}
  
// This code is contributed by vt_m.

chevron_right


PHP

filter_none

edit
close

play_arrow

link
brightness_4
code

<?php
// PHP Program to check whether
// number is semiprime or not
  
// Utility function to check whether
// number is semiprime or not
function checkSemiprime($num)
{
    $cnt = 0;
  
    for ( $i = 2; $cnt < 2 && 
          $i * $i <= $num; ++$i)
        while ($num % $i == 0)
            $num /= $i
              
            // Increment count of
            // prime numbers
               ++$cnt
  
    // If number is greater than 1,
    // add it to the count variable 
    // as it indicates the number 
    // remain is prime number
    if ($num > 1)
        ++$cnt;
  
    // Return '1' if count is 
    // equal to '2' 
    // else return '0'
    return $cnt == 2;
}
  
// Function to print 'True' or 'False'
// according to condition of semiprime
function semiprime($n)
{
    if (checkSemiprime($n))
        echo "True\n";
    else
        echo "False\n";
}
  
// Driver code
$n = 6;
semiprime($n);
  
$n = 8;
semiprime($n);
  
// This code is contributed by anuj_67.
?>

chevron_right



Output :

True
False

Time complexity: O(\sqrt n)
Auxiliary space: O(1)

Reference: https://en.wikipedia.org/wiki/Semiprime



My Personal Notes arrow_drop_up

Check out this Author's contributed articles.

If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.

Please Improve this article if you find anything incorrect by clicking on the "Improve Article" button below.



Improved By : vt_m