Question

How to find the two prime numbers of a number whose sum is equal to the number itself in C++

Answer 1

#include <iostream>

bool isPrime(int n) {
    if (n <= 1) return false;
    
    for (int i = 2; i <= n / 2; ++i) {
        if (n % i == 0) return false;
    }
    
    return true;
}

int main() {
    int n = 38;
    bool found = false;

    for (int i = 2; i <= n / 2; ++i) {
        if (isPrime(i) && isPrime(n - i) && i != (n - i)) {
            std::cout << n << " = " << i << " + " << n - i << "\n";
            found = true;
        }
    }

    if (!found) {
        std::cout << "Not Found\n";
    }
}


/*
run:
   
38 = 7 + 31
            
*/

 

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