Question

How to check whether a given number is a twisted prime number in C#

Answer 1

using System;
 
// A number is a twisted prime number if the reverse of the number is also a prime number
 
class Program
{
    static int reverseNumber(int n) {
        int reverse = 0, reminder;
      
        while (n != 0) {
            reminder = n % 10;
            reverse = reverse * 10 + reminder;
            n = n / 10;
        }
        return reverse;
    }
  
    static bool isPrime(int n) {
        if (n < 2 || (n % 2 == 0 && n != 2)) {
            return false;
        }
      
        int count = (int)Math.Floor(Math.Sqrt(n));
        for (int i = 3; i <= count; i += 2) {
            if (n % i == 0) {
                return false;
            }
        }
        return true;
    }
    static void Main() {
        int n = 79;
        int reverse_n = reverseNumber(n);
  
        if (isPrime(n) && isPrime(reverse_n)) {
            Console.Write("Twisted prime number");
        } else {
            Console.Write("Not twisted prime number");
        }
    }
}
 
 
 
/*
run:
  
Twisted prime number
  
*/

 

 

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