a006: 一元二次方程式 FYI: https://yunlinsong.blogspot.com/2016/01/blog-post_29.html

a006.cpp

#include <iostream>
#include <cmath>

using namespace std;

int main()
{
    double a, b, c;

    while( cin >> a >> b >> c )
    {
        int check = b * b - 4 * a * c;
        bool noRoot =  check < 0;
        if( noRoot == true )
        {
            cout << "No real root" << endl;
        }
        else
        {
            if( check == 0 )
            {
                int x = -b / (2 * a);
                cout << "Two same roots x=" << x << endl;
            }
            else
            {
                int x1 = (-b + sqrtl(check)) / (2 * a);
                int x2 = (-b - sqrtl(check)) / (2 * a);
                cout << "Two different roots x1=" << x1 << " , x2=" << x2 << endl;
            }
        }
    }

    return 0;
}