HDU 3714

 1 最大值最小问题，三分。。。。竟然排第六当时。。。。。
 2 #include<stdio.h>
 3 
 4 #include<string.h>
 5 #define max 10000+10
 6 #define Max(x,y) (x>y?x:y)
 7 #define Min(x,y) (x<y?x:y)
 8 #define inf 1e-8
 9 
10 typedef long long LL;
11 int a[max],b[max],c[max];
12 int t,n;
13 
14 double func(int a,int b,int c,double x){
15     return a*x*x+b*x+c;
16 }
17 
18 double solve(double x){
19         double res=func(a[0],b[0],c[0],x);
20         for(int i=1;i<n;i++){
21             res=Max(res,func(a[i],b[i],c[i],x));
22         }
23         return res;
24 }
25 
26 int main(){
27     scanf("%d",&t);
28     while(t--){
29         scanf("%d",&n);
30         for(int i=0;i<n;i++){
31             scanf("%d%d%d",&a[i],&b[i],&c[i]);
32         }
33         double left=0.0,right=1000.0;
34         while(right-left>inf){
35             double mid=(left+right)*0.5;
36             double mmid=(left+mid)*0.5;
37             double res1=solve(mid);
38             double res2=solve(mmid);
39             if(res2-res1>inf){
40                 left=mmid;
41             }
42             else{
43                 right=mid;
44             }
45         }
46         double ans=solve(left);
47         printf("%.4lf
",ans);
48     }
49 }