HDU 2899

 1 #include <stdio.h>
 2 #include <math.h>
 3 const double mm = 1e-8;
 4 double y;
 5 double cal(double x){
 6     return 42.0*pow(x,6.0)+48.0*pow(x,5.0)+21.0*pow(x,2.0)+10.0*x;
 7 }
 8 double ans(double x){
 9     return 6.0*pow(x,7.0)+8.0*pow(x,6.0)+7.0*pow(x,3.0)+5.0*pow(x,2.0)-y*x;
10 }
11 int main()
12 {
13     int t;scanf("%d",&t);
14     while(t--){
15         scanf("%lf",&y);
16         if(cal(100.0)-y<=0.0){
17             printf("%.4lf\n",ans(100.0));
18             continue;
19         }
20         double l=0,r=100,mid;
21         while(r-l>mm){
22             mid=(l+r)/2.0;
23             if(cal(mid)-y>0.0)    r=mid;
24             else                l=mid;
25         }
26         printf("%.4lf\n",ans(mid));
27     }
28 }