题解

#include <iostream>
#include <cstdio>
using namespace std;
int main()
{
double a,b,c,d;
scanf("%lf%lf%lf%lf",&a,&b,&c,&d);
for(double i=-100;i<=100;i+=0.001)
{
double j=i+0.001;
double y1=aiii+bii+ci+d;
double y2=ajjj+bjj+cj+d;
if(y1>=0&&y2<=0||y1<=0&&y2>=0)
{
double x=(i+j)/2;
printf("%.2lf ",x);
}
}
}