杭电二分题

Description

Now, here is a fuction: 
  F(x) = 6 * x^7+8*x^6+7*x^3+5*x^2-y*x (0 <= x <=100) 
Can you find the minimum value when x is between 0 and 100.

 

Input

The first line of the input contains an integer T(1<=T<=100) which means the number of test cases. Then T lines follow, each line has only one real numbers Y.(0 < Y <1e10)

 

Output

Just the minimum value (accurate up to 4 decimal places),when x is between 0 and 100.

 

Sample Input

     
     
     
     

      
      
      
       2
100
200 
     
     
     
     

 

Sample Output

     
     
     
     

      
      
      
      
         -74.4291
-178.8534 
     
     
     
     

 

#include<iostream>
#include <iomanip>
using namespace std;
long double fun(double x)
{
	return 42*x*x*x*x*x*x+48*x*x*x*x*x+21*x*x+10*x ;
}
long double fun1(double x,double y)
{
	return 6*x*x*x*x*x*x*x+8*x*x*x*x*x*x+7*x*x*x+5*x*x - y*x ;
}
int main()
{
	int t;
	long double y,hight=100,low=0,mid,k;
	cin >> t ;
	while(t--)
	{
		cin >> y;
		hight=100;
		low=0;
		while(hight - low >1e-8)
		{
			mid=(hight + low)/2;
			k=fun(mid);
			if(k>y)
			{
				hight=mid;
			}
			if(k<y)
			{
				low=mid;
			}
		}
		cout << setiosflags(ios::fixed) ;
		cout << setprecision(4) << fun1(mid , y) << endl;
	}
	return 0;
}