HDU 2199

 1 #include<iostream>
 2 #include<algorithm>
 3 #include<cmath>
 4 #include<cstdio>
 5 using namespace std;
 6 double f(double x)
 7 {
 8     return 8*pow(x,4.0)+7*pow(x,3.0)+2*pow(x,2.0)+3*x + 6;
 9 }
10 int main()
11 {
12     int n;cin >> n;
13     while(n--){
14         double y;cin >> y;
15         if(f(0.0)<=y&&f(100.0)>=y){
16             double left=0,right=100;
17             double mid;
18             while(right-left>1e-6){
19                 mid=(left+right)/2;
20                 double ans=f(mid);
21                 if(ans>y)    right=mid+1e-7;
22                 else        left=mid-1e-7;
23                 mid=(left+right)/2.0;
24             }
25             printf("%.4lf\n",(left+right)/2.0);
26         }
27         else    cout << "No solution!\n";
28     }
29 }