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[0],b[0],c[0],x);
        for(int i=1;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=0;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
",ans);
    }
}