Count of prime digits of a Number which divides the number

Given an integer N, the task is to count the number of digits in N which is a prime number and also divides the number.

Examples:

Input: N = 12
Output: 1
Explanation:
Digits of the number = {1, 2}
But, only 2 is prime number that divides N.

Input: N = 1032
Output: 2
Explanation:
Digits of the number = {1, 0, 3, 2}
3 and 2 divides the number and are also prime.

Naive Approach: The idea is to find all the digits of the number. For each digit, check if is prime or not. If yes, then check if it divides the number or not. If both the cases are true, then increment the count by 1. The final count is the required answer.



Efficient Approach: Since only 2, 3, 5 and 7 are the prime single-digit numbers, therefore for each digit, check if divides the number and if is 2, 3, 5 or 7. If both the cases are true, then increment the count by 1. The final count is the required answer.

Below is implementation of this approach:

C++

filter_none

edit
close

play_arrow

link
brightness_4
code

// C++ program to count number of digits
// which is prime and also divides number
  
#include <bits/stdc++.h>
  
using namespace std;
  
// Function to find the number of
// digits in number which divides the
// number and is also a prime number
int countDigit(int n)
{
    bool prime[10];
    memset(prime, false, sizeof(prime));
  
    // Only 2, 3, 5 and 7 are prime 
    // one-digit number
    prime[2] = prime[3] = true;
    prime[5] = prime[7] = true;
  
    int temp = n, count = 0;
      
    // Loop to compute all the digits
    // of the number untill it 
    // is not equal to the zero
    while (temp != 0) {
  
        // Fetching each digit
        // of the number
        int d = temp % 10;
  
        temp /= 10;
  
        // Checking if digit is greater than 0
        // and can divides n and is prime too
        if (d > 0 && n % d == 0 && prime[d])
            count++;
    }
  
    return count;
}
  
// Driven Code
int main()
{
    int n = 1032;
  
    cout << countDigit(n) << endl;
    return 0;
}

chevron_right


Java

filter_none

edit
close

play_arrow

link
brightness_4
code

// Java program to count number of digits
// which is prime and also divides number
class GFG {
      
    // Function to find the number of
    // digits in number which divides the
    // number and is also a prime number
    static int countDigit(int n)
    {
        boolean prime[]  = new boolean[10];
          
        for (int i = 0; i < 10; i++)
            prime[i] = false;
  
        // Only 2, 3, 5 and 7 are prime 
        // one-digit number
        prime[2] = prime[3] = true;
        prime[5] = prime[7] = true;
      
        int temp = n, count = 0;
          
        // Loop to compute all the digits
        // of the number untill it 
        // is not equal to the zero
        while (temp != 0) {
      
            // Fetching each digit
            // of the number
            int d = temp % 10;
      
            temp /= 10;
      
            // Checking if digit is greater than 0
            // and can divides n and is prime too
            if (d > 0 && n % d == 0 && prime[d] == true)
                count++;
        }
      
        return count;
    }
      
    // Driven Code
    public static void main (String[] args)
    {
        int n = 1032;
      
        System.out.println(countDigit(n)) ;
    }
}
  
// This code is contributed by Yash_R

chevron_right


Python3

filter_none

edit
close

play_arrow

link
brightness_4
code

# Python program to count number of digits
# which is prime and also divides number
  
# Function to find the number of
# digits in number which divides the
# number and is also a prime number
def countDigit(n):
    prime = [False]*10
  
    # Only 2, 3, 5 and 7 are prime 
    # one-digit number
    prime[2] = True
    prime[3] = True;
    prime[5] = True
    prime[7] = True;
  
    temp = n
    count = 0;
      
    # Loop to compute all the digits
    # of the number untill it 
    # is not equal to the zero
    while (temp != 0):
          
        # Fetching each digit
        # of the number
        d = temp % 10;
  
        temp //= 10;
  
        # Checking if digit is greater than 0
        # and can divides n and is prime too
        if (d > 0 and n % d == 0 and prime[d]):
            count += 1
  
    return count
  
# Driver Code
n = 1032
  
print(countDigit(n))
  
# This code is contributed by ANKITKUMAR34

chevron_right


C#

filter_none

edit
close

play_arrow

link
brightness_4
code

// C# program to count number of digits
// which is prime and also divides number
using System;
  
class GFG {
      
    // Function to find the number of
    // digits in number which divides the
    // number and is also a prime number
    static int countDigit(int n)
    {
        bool []prime  = new bool[10];
          
        for (int i = 0; i < 10; i++)
            prime[i] = false;
  
        // Only 2, 3, 5 and 7 are prime 
        // one-digit number
        prime[2] = prime[3] = true;
        prime[5] = prime[7] = true;
      
        int temp = n, count = 0;
          
        // Loop to compute all the digits
        // of the number untill it 
        // is not equal to the zero
        while (temp != 0) {
      
            // Fetching each digit
            // of the number
            int d = temp % 10;
      
            temp /= 10;
      
            // Checking if digit is greater than 0
            // and can divides n and is prime too
            if (d > 0 && n % d == 0 && prime[d] == true)
                count++;
        }
      
        return count;
    }
      
    // Driven Code
    public static void Main (string[] args)
    {
        int n = 1032;
      
        Console.WriteLine(countDigit(n)) ;
    }
}
  
// This code is contributed by Yash_R

chevron_right


Output:

2

Don’t stop now and take your learning to the next level. Learn all the important concepts of Data Structures and Algorithms with the help of the most trusted course: DSA Self Paced. Become industry ready at a student-friendly price.




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 : ANKITKUMAR34, Yash_R