📜  检查N是否为弱质数

📅  最后修改于: 2021-05-06 18:35:30             🧑  作者: Mango

给定正整数N ,任务是检查N是否为弱质数。

例子:

方法:

  • 如果N不是素数或它是第一个素数,即2,则打印No。
  • 否则,找到最接近N的素数(左边一个,右边一个),并将它们的算术平均值存储在mean中
    • 如果N <表示打印
    • 其他打印

下面是上述方法的实现:

C++14
// C++ program to check
// if a given number is weak prime
#include 
using namespace std;
 
// Utility function to check
// if a number is prime or not
bool isPrime(int n)
{
     
    // Corner cases
    if (n <= 1)
        return false;
    if (n <= 3)
        return true;
 
    // This is checked so that we can skip
    // middle five numbers in below loop
    if (n % 2 == 0 || n % 3 == 0)
        return false;
 
    for(int i = 5; i * i <= n; i = i + 6)
        if (n % i == 0 || n % (i + 2) == 0)
            return false;
 
    return true;
}
 
// Function that returns true
// if n is a weak prime
bool isWeakPrime(int n)
{
     
    // If n is not a prime number or
    // n is the first prime then return false
    if (!isPrime(n) || n == 2)
        return false;
 
    // Initialize previous_prime to n - 1
    // and next_prime to n + 1
    int previous_prime = n - 1;
    int next_prime = n + 1;
 
    // Find next prime number
    while (!isPrime(next_prime))
        next_prime++;
 
    // Find previous prime number
    while (!isPrime(previous_prime))
        previous_prime--;
 
    // Arithmetic mean
    int mean = (previous_prime +
                next_prime) / 2;
 
    // If n is a weak prime
    if (n < mean)
        return true;
    else
        return false;
}
 
// Driver code
int main()
{
    int n = 13;
 
    if (isWeakPrime(n))
        cout << "Yes";
    else
        cout << "No";
 
    return 0;
}
 
// This code is contributed by himanshu77


Java
// Java program to check
// if a given number is weak prime
import java.util.*;
class GFG{
 
// Utility function to check
// if a number is prime or not
static boolean isPrime(int n)
{
    // Corner cases
    if (n <= 1)
        return false;
    if (n <= 3)
        return true;
 
    // This is checked so that we can skip
    // middle five numbers in below loop
    if (n % 2 == 0 || n % 3 == 0)
        return false;
 
    for (int i = 5; i * i <= n; i = i + 6)
        if (n % i == 0 || n % (i + 2) == 0)
            return false;
 
    return true;
}
 
// Function that returns true
// if n is a weak prime
static boolean isWeakPrime(int n)
{
    // If n is not a prime number or
    // n is the first prime then return false
    if (!isPrime(n) || n == 2)
        return false;
 
    // Initialize previous_prime to n - 1
    // and next_prime to n + 1
    int previous_prime = n - 1;
    int next_prime = n + 1;
 
    // Find next prime number
    while (!isPrime(next_prime))
        next_prime++;
 
    // Find previous prime number
    while (!isPrime(previous_prime))
        previous_prime--;
 
    // Arithmetic mean
    int mean = (previous_prime +
                next_prime) / 2;
 
    // If n is a weak prime
    if (n < mean)
        return true;
    else
        return false;
}
 
// Driver code
public static void main(String args[])
{
    int n = 13;
 
    if (isWeakPrime(n))
        System.out.print("Yes");
    else
        System.out.print("No");
}
}
 
// This code is contributed by Code_Mech


Python3
# Python3 program to check if a given
# number is weak prime
 
# Utility function to check
# if a number is prime or not
def isPrime(n):
     
    # Corner cases
    if (n <= 1):
        return False
    if (n <= 3):
        return True
 
    # This is checked so that we can skip
    # middle five numbers in below loop
    if (n % 2 == 0 or n % 3 == 0):
        return False
 
    i = 5
    while (i * i <= n):
        if (n % i == 0 or n % (i + 2) == 0):
            return False
        i = i + 6
 
    return True
 
# Function that returns true
# if n is a weak prime
def isWeakPrime(n):
 
    # declaring variables as global
    global next_prime, previous_prime
 
    # If n is not a prime number or n is
    # the first prime then return false
    if(not isPrime(n) or n == 2):
        return False
 
    # Initialize previous_prime to n - 1
    # and next_prime to n + 1
    previous_prime = n - 1
    next_prime = n + 1
 
    # Find next prime number
    while(not isPrime(next_prime)):
        next_prime += 1
 
    # Find previous prime number
    while (not isPrime(previous_prime)):
        previous_prime -= 1
 
    # Arithmetic mean
    mean = (previous_prime + next_prime) // 2
 
    # If n is a weak prime
    if(n < mean):
        return True
    else:
        return False
 
# Driver code
if __name__ == '__main__':
 
    n = 13
 
    if(isWeakPrime(n)):
        print("Yes")
    else:
        print("No")
 
# This code is contributed by Shivam Singh


C#
// C# program to check if a given number is weak prime
using System;
class GFG {
 
    // Utility function to check
    // if a number is prime or not
    static bool isPrime(int n)
    {
        // Corner cases
        if (n <= 1)
            return false;
        if (n <= 3)
            return true;
 
        // This is checked so that we can skip
        // middle five numbers in below loop
        if (n % 2 == 0 || n % 3 == 0)
            return false;
 
        for (int i = 5; i * i <= n; i = i + 6)
            if (n % i == 0 || n % (i + 2) == 0)
                return false;
 
        return true;
    }
 
    // Function that returns true
    // if n is a weak prime
    static bool isWeakPrime(int n)
    {
        // If n is not a prime number or
        // n is the first prime then return false
        if (!isPrime(n) || n == 2)
            return false;
 
        // Initialize previous_prime to n - 1
        // and next_prime to n + 1
        int previous_prime = n - 1;
        int next_prime = n + 1;
 
        // Find next prime number
        while (!isPrime(next_prime))
            next_prime++;
 
        // Find previous prime number
        while (!isPrime(previous_prime))
            previous_prime--;
 
        // Arithmetic mean
        int mean = (previous_prime
                    + next_prime)
                   / 2;
 
        // If n is a weak prime
        if (n < mean)
            return true;
        else
            return false;
    }
 
    // Driver code
    public static void Main()
    {
        int n = 13;
 
        if (isWeakPrime(n))
            Console.WriteLine("Yes");
        else
            Console.WriteLine("No");
    }
}


Javascript


输出:
Yes