HDU 2199 Can you solve this equation?

http://acm.hdu.edu.cn/showproblem.php?pid=2199

Problem Description

Now,given the equation 8*x^4 + 7*x^3 + 2*x^2 + 3*x + 6 == Y,can you find its solution between 0 and 100;
Now please try your lucky.

 

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 a real number Y (fabs(Y) <= 1e10);

 

Output

For each test case, you should just output one real number(accurate up to 4 decimal places),which is the solution of the equation,or “No solution!”,if there is no solution for the equation between 0 and 100.

 

Sample Input

   
   
   
   

    
    
    
    2
100
-4
   
   
   
   

 

Sample Output

   
   
   
   

    
    
    
    1.6152
No solution!
   
   
   
   
   
   
   
   


   
   
   
   

#include <stdio.h>
#include <iostream>
#include <cmath>
using namespace std;
double y;
double fc(double x)
{
    return 8*pow(x,4)+7*pow(x,3)+2*x*x+x*3+6-y;
}
int main()
{
    int n;
    scanf("%d",&n);
    while(n--)
    {
        double l=0;
        double r=100;
        double x=-1;
        scanf("%lf",&y);
        if(fc(0)>0||fc(100.0)<0)
        {
            printf("No solution!\n");
            continue;
        }
        else
        {
            while(l<r)
            {
                double mid=(l+r)/2;
                if(fc(mid)<0.000001&&fc(mid)>-0.000001)
                {
                    x=mid;
                    break;
                }
                else if(fc(mid)<0)
                    l=mid;
                else
                    r=mid;
            }
            if(x==-1)
                printf("No solution!\n");
            else
                printf("%.4f\n",x);
        }
    }
    return 0;
}