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) {
        if(a==0){printf("Not quadratic equation\n");}
        else{
            double o=b*b-4*a*c;
            double x1=(-b+sqrt(o))/(2*a);
            double x2=(-b-sqrt(o))/(2*a);
            if(o==0){if(x1==-0.0)x1=x1+0;//-0+0=0
                printf("x1=x2=%.2f\n",x1);
            }
            else if(o>0){
                if(x1>x2){double k=x2;
                x2=x1;x1=k;}
                printf("x1=%.2f;x2=%.2f\n",x1,x2);
            }
            else {
                    double k=-b/(2*a);
                    double k1=sqrt(-o)/(2*a);
                printf("x1=%.2f-%.2fi;x2=%.2f+%.2fi\n",k,k1,k,k1);
            }
        }
    }    
    return 0;
}