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): 2458    Accepted Submission(s): 1234

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<math.h>
double y;
int flag;
double find(double mid)
{
 double ans;
 ans=8*mid*mid*mid*mid+7*mid*mid*mid+2*mid*mid+3*mid+6;
 return ans;
}
int main()
{
    int cas;
 double mid,start,end; 
 scanf("%d",&cas);
 while(cas--)
 {
  scanf("%lf",&y);
  flag=0;
  if(find(0)<=y&&find(100)>=y)//这个才是判断是否存在的关键条件
  {
   start=0;end=100;
   while(end-start>0.0000001)//这个地方要尽量小 当为10的负6次方 仍旧不能达到样例数据中的精度 但是能AC
   {                          //所以以后做关于精度的题目 尽量小些 反正也不会对题目产生什么大影响
    mid=(start+end)/2;
    if(find(mid)>y)  end=mid;
    else //if(find(mid)<y)
     start=mid;
   }
   printf("%.4lf\n",(start+end)/2);
  }
  else  printf("No solution!\n");
 }
 return 0;
}