1435：曲線

 

#define E 1e-11
const int N=1e4+5;

    int n,m,t;
    int i,j,k;
    double a[N],b[N],c[N];
double H,h,D;
double C(double x){
    double maxx=-1;
    for(i=0;i<n;i++){
        maxx=max(a[i]*x*x+b[i]*x+c[i],maxx);
    }
    return maxx;
}
int main()
{
    IOS;
	rush(){
        cin>>n;
        for(i=0;i<n;i++) cin>>a[i]>>b[i]>>c[i];
        double l=0,r=1000;
        while(r-l>E){
            double mid=(l+r)/2.0;
            double midmid=(r+mid)/2.0;
            if(C(mid) > C(midmid)) l=mid;//先遞減後遞增
            else r=midmid;
        }
        pf(C(l));
    }
    //PAUSE;
	return 0;
}