题解 | #计算一元二次方程#

#include <stdio.h>
#include<math.h>

int main() {
    double a, b, c;
    while (scanf("%lf %lf %lf", &a, &b, &c) != EOF) {
        double m = b * b - 4 * a * c;
        if (a == 0)
            printf("Not quadratic equation\n");
        else {
            double x1 = (-b - sqrt(m)) / (2 * a), x2 = (-b + sqrt(m)) / (2 * a);
            if(x2==-0)
            x2=0;
            if (m == 0) {
                printf("x1=x2=%.2lf\n", x2);
            }
            else if(m>0)
            printf("x1=%.2lf;x2=%.2lf\n",x1,x2);
            else{
                double y1=-b/(2*a),y2=sqrt(-m)/(2*a);
            if(a>0){
                printf("x1=%.2lf-%.2lfi;x2=%.2lf+%.2lfi\n",y1,y2,y1,y2); 
            }
            else {
            printf("x1=%.2lf%.2lfi;x2=%.2lf%.2lfi\n",y1,y2,y1,y2); 
            }
            }
        }
    }
    return 0;
}