检查一个素数是否可以表示为两个素数之和

Input : N = 13
Output : Yes
Explanation : The number 13 can be written as 11 + 2,
here 11 and 2 are both prime.
Input : N = 11
Output : No


// C++ program to check if a prime number
// can be expressed as sum of
// two Prime Numbers
#include
using namespace std;
// Function to check whether a number
// is prime or not
bool isPrime(int n)
{
    if (n <= 1)
        return false;
    for (int i = 2; i <= sqrt(n); i++) {
        if (n % i == 0)
            return false;
    }
    return true;
}
// Function to check if a prime number
// can be expressed as sum of
// two Prime Numbers
bool isPossible(int N)
{
    // if the number is prime,
    // and number-2 is also prime
    if (isPrime(N) && isPrime(N - 2))
        return true;
    else
        return false;
}
// Driver code
int main()
{
    int n = 13;
    if (isPossible(n))
        cout << "Yes";
    else
        cout << "No";
    return 0;
}


// Java program to check if a prime number
// can be expressed as sum of
// two Prime Numbers
public class GFG{
    // Function to check whether a number
    // is prime or not
    static boolean isPrime(int n)
    {
        if (n <= 1)
            return false;
        for (int i = 2; i <= Math.sqrt(n); i++) {
            if (n % i == 0)
                return false;
        }
        return true;
    }
    // Function to check if a prime number
    // can be expressed as sum of
    // two Prime Numbers
    static boolean isPossible(int N)
    {
        // if the number is prime,
        // and number-2 is also prime
        if (isPrime(N) && isPrime(N - 2))
            return true;
        else
            return false;
    }
     // Driver code
     public static void main(String []args){
        int n = 13;
        if (isPossible(n) == true)
            System.out.println("Yes");
        else
            System.out.println("No");
     }
     // This code is contributed by ANKITRAI1
}


# Python3 program to check if a prime
# number can be expressed as sum of
# two Prime Numbers
import math
# Function to check whether a number
# is prime or not
def isPrime(n):
    if n <= 1:
        return False
    if n == 2:
        return True
    if n%2 == 0:
        return False
    for i in range(3, int(math.sqrt(n))+1, 2):
        if n%i == 0:
            return False
    return True
# Function to check if a prime number
# can be expressed as sum of
# two Prime Numbers
def isPossible(n):
    # if the number is prime,
    # and number-2 is also prime
    if isPrime(n) and isPrime(n - 2):
        return True
    else:
        return False
# Driver code
n = 13
if isPossible(n) == True:
    print("Yes")
else:
    print("No")
# This code is contributed by Shrikant13


// C# program to check if a prime
// number can be expressed as sum
// of two Prime Numbers
using System;
class GFG
{
// Function to check whether a
// number is prime or not
static bool isPrime(int n)
{
    if (n <= 1)
        return false;
    for (int i = 2;
             i <= Math.Sqrt(n); i++)
    {
        if (n % i == 0)
            return false;
    }
    return true;
}
// Function to check if a prime
// number can be expressed as sum
// of two Prime Numbers
static bool isPossible(int N)
{
    // if the number is prime,
    // and number-2 is also prime
    if (isPrime(N) && isPrime(N - 2))
        return true;
    else
        return false;
}
// Driver code
public static void Main()
{
    int n = 13;
    if (isPossible(n) == true)
        Console.Write("Yes");
    else
        Console.Write("No");
}
}
// This code is contributed
// by ChitraNayal



// PHP program to check if a prime
// number can be expressed as sum
// of two Prime Numbers
// Function to check whether a
// number is prime or not
function isPrime($n)
{
    if ($n <= 1)
        return false;
    for ($i = 2; $i <= sqrt($n); $i++)
    {
        if ($n % $i == 0)
            return false;
    }
    return true;
}
// Function to check if a prime
// number can be expressed as sum
// of two Prime Numbers
function isPossible($N)
{
    // if the number is prime,
    // and number-2 is also prime
    if (isPrime($N) && isPrime($N - 2))
        return true;
    else
        return false;
}
// Driver code
$n = 13;
if (isPossible($n))
    echo ("Yes");
else
    echo("No");
// This code is contributed
// by Shivi_Aggarwal
?>


Yes