hdu 2199 二分

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!
 
/*
此题显然是用二分。
这个代码运行样例结果是1.6151 不过也能AC 醉了- -
*/
 
 
代码：
#include<iostream>
#include<algorithm>
#include<cmath>
#include<cstdlib>
using namespace std;
double f(double x)
{
	return pow(x,4)*8+pow(x,3)*7+pow(x,2)*2+3*x+6;
}
int main()
{
	int t;
	double y,mid,left,right;
	cin>>t;
	while(t--)
	{
		cin>>y;
		if(f(0)<=y&&f(100)>=y)
		{
		
		left=0;
		right=100;
	
		while(right-left>=1e-7)
		{
				mid=(left+right)/2;
			if(f(mid)>y)
				right=mid;
			else if(f(mid)<y)
				left=mid;
		}
		printf("%.4f\n",mid);
		}
		else
			printf("No solution!\n");
	}
	return 0;
}