HDU 3714

 最大值最小问题，三分。。。。竟然排第六当时。。。。。
 #include<stdio.h>

 #include<string.h>
 #define max 10000+10
 #define Max(x,y) (x>y?x:y)
 #define Min(x,y) (x<y?x:y)
 #define inf 1e-8

 typedef long long LL;
 int a[max],b[max],c[max];
 int t,n;

 double func(int a,int b,int c,double x){
     return a*x*x+b*x+c;
 }

 double solve(double x){
         double res=func(a[],b[],c[],x);
         for(int i=;i<n;i++){
             res=Max(res,func(a[i],b[i],c[i],x));
         }
         return res;
 }

 int main(){
     scanf("%d",&t);
     while(t--){
         scanf("%d",&n);
         for(int i=;i<n;i++){
             scanf("%d%d%d",&a[i],&b[i],&c[i]);
         }
         double left=0.0,right=1000.0;
         while(right-left>inf){
             double mid=(left+right)*0.5;
             double mmid=(left+mid)*0.5;
             double res1=solve(mid);
             double res2=solve(mmid);
             if(res2-res1>inf){
                 left=mmid;
             }
             else{
                 right=mid;
             }
         }
         double ans=solve(left);
         printf("%.4lf\n",ans);
     }
 }