C++ programming more efficient way to do

Question

This program is running but I am looking for a more efficient way to run this program. You can see I commented out the code because I think it can work out without that extra code. however, I am a little bit confused. in the else statement, I am trying to decrement the x value so it becomes x=8 and runs the loop again and decrement again. But it is not working. can anyone help me what should I do? thanks.

#include <iostream>

#include <cmath>

using namespace std;

int main()
{
    int x, y;

    if (x = 9) {
        for (y = 0; y < 9; y++)
            if (3 * pow (x, 2) + 4* pow(y, 2) == 271)
                cout << "x value is : " << x << endl << "y value is: " << y<<endl;
            else {
                x--;

            }
    }
    /*   if (x = 8) {
        for (y = 0; y < 9; y++)
            if (3 * pow(x, 2) + 4 * pow(y, 2) == 271)
                cout << "x value is : " << x << endl << "y value is: " << y<<endl;
    }
     if (x = 7) {
        for (y = 0; y < 9; y++)
            if (3 * pow(x, 2) + 4 * pow(y, 2) == 271)
                cout << "x value is : " << x << endl << "y value is: " << y<<endl;
    }
     if (x = 6) {
        for (y = 0; y < 9; y++)
            if (3 * pow(x, 2) + 4 * pow(y, 2) == 271)
                cout << "x value is : " << x << endl << "y value is: " << y<<endl;
    }
     if (x = 5) {
        for (y = 0; y < 9; y++)
            if (3 * pow(x, 2) + 4 * pow(y, 2) == 271)
                cout << "x value is : " << x << endl << "y value is: " << y<<endl;
    }
     if (x = 4) {
        for (y = 0; y < 9; y++)
            if (3 * pow(x, 2) + 4 * pow(y, 2) == 271)
                cout << "x value is : " << x << endl << "y value is: " << y<<endl;
    }
     if (x = 3) {
         for (y = 0; y < 9; y++)
             if (3 * pow(x, 2) + 4 * pow(y, 2) == 271)
                 cout << "x value is : " << x << endl << "y value is: " << y<<endl;
    }
     if (x = 2) {
        for (y = 0; y < 9; y++)
            if (3 * pow(x, 2) + 4 * pow(y, 2) == 271)
                cout << "x value is : " << x << endl << "y value is: " << y<<endl;
    }
     if (x = 1) {
        for (y = 0; y < 9; y++)
            if (3 * pow(x, 2) + 4 * pow(y, 2) == 271)
                cout <<"x value is : "<< x <<endl<<"y value is: "<< y<<endl;
    }

    */

    system("pause");
    return 0;
}

Answer 1

Just use a for loop to iterate over values of x:

for (x = 9; x > 0; x--) {
    for (y = 0; y < 9; y++) {
        if (3 * pow (x, 2) + 4* pow(y, 2) == 271) {
            cout << "x: " << x << endl << "y: " << y << endl;
        }
    }
}