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 the implementation of this approach:
C++
// 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 until 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; } |
Java
// Java program to count number of digits // which is prime and also divides number import java.io.*; 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 until 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 |
Python3
# 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 until 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 |
C#
// 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 until 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 |
Javascript
<script> // Javascript 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 function countDigit(n) { var prime = Array(10).fill( false ); // Only 2, 3, 5 and 7 are prime // one-digit number prime[2] = prime[3] = true ; prime[5] = prime[7] = true ; var temp = n, count = 0; // Loop to compute all the digits // of the number until it // is not equal to the zero while (temp != 0) { // Fetching each digit // of the number var d = temp % 10; temp = parseInt(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 n = 1032; document.write(countDigit(n)); </script> |
2
Time Complexity: O(log10n)
Auxiliary Space: O(prime)
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