杭电2199Can you solve this equation?（初试二分法)

 

Can you solve this equation?

Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others)
Total Submission(s): 13000    Accepted Submission(s): 5822

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!
   
   
   
   

 

Author

Redow

 

#include<stdio.h>
#include<math.h>
	double fun(double x)
	{
		return 8*x*x*x*x+7*x*x*x+2*x*x+3*x+6;
	}
	int main()
	{
		int n;
		double y,l,r,mid;
		scanf("%d",&n);
		while(n--)
		{
			scanf("%lf",&y);
		l=0.0;
		r=100.0;
		if(y<fun(l)||y>fun(r))//因为其为递增序列则fun（l）为最小值，fun（r）为最大值 
		{
		printf("No solution!\n");
		continue;//停止while循环进行下一次while循环 
		}
		while(r-l>1e-10)//二分法模板：死记！！！！！！ 
		{
			mid=(r+l)/2.0;
			if(fun(mid)<y)
			l=mid+1e-10;
			else
			r=mid-1e-10;
		}
		printf("%.4lf\n",mid);
		}
		return 0;
}