hdu2199 Can you solve this equation?

最新推荐文章于 2021-04-09 16:43:57 发布

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最新推荐文章于 2021-04-09 16:43:57 发布

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分类专栏：二分查找

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本文介绍了一个具体的数值求解多项式方程的问题，并提供了一段使用二分法进行求解的C++代码示例。该算法能够在给定精度范围内找到特定多项式在0到100区间内的根。

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Can you solve this equation?

Time Limit: 2000/1000 MS (Java/Others) Memory Limit: 32768/32768 K (Java/Others)
Total Submission(s): 13731 Accepted Submission(s): 6115

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<iostream>
#include<stdio.h>
#include<math.h>
using namespace std;
double fan(double x){
	return 8*pow(x,4)+7*pow(x,3)+2*pow(x,2)+3*x+6;
}
double Binsearch(double l,double h,double k){
	double mid;
	while(h-l>1e-10)   //精度
	{
		mid=(h+l)/2;
		if(fan(mid)>k) h=mid;
		else l=mid;
	}
	return mid;
}
int main()
{
    int T;
    double s;
    cin>>T;
    while(T--)
    {
        cin>>s;
        if(fan(1)>s||fan(100)<s)
	cout<<"No solution!\n";
	else printf("%.4lf\n",Binsearch(0,100,s));
    }
    return 0;
}