hdu 2199 Can you solve this equation?

Can you solve this equation?

Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others)
Total Submission(s): 5413    Accepted Submission(s): 2568

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!

 

 二分入门题

#include<stdio.h>
#include<math.h>
double y;
double solve(double x)
{
     double n;
     n=8*x*x*x*x + 7*x*x*x + 2*x*x + 3*x + 6;
     return n;
}
int main()
{
     int t;
     double y,l,r,p,mid;
     scanf("%d",&t);
     while(t--)
     {
          scanf("%lf",&y);
          if(solve(0)>y||solve(100)<y)
          {
               printf("No solution!
");
               continue;
          }
          l=0.0,r=100.0;
          while(r-l>1e-9)
          {
               mid=(r+l)/2;
               p=solve(mid);
               if(p<y)
               l=mid;
               else
               r=mid;
          }
          printf("%.4lf
",mid);
     }
     return 0;
}