Strange fuction 三分

最新推荐文章于 2025-06-23 08:56:55 发布

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本文介绍了一个关于多项式函数在特定区间内寻找最小值的问题。通过三分法算法，该文详细解释了如何针对输入的不同参数Y，计算并输出函数在0到100区间内的最小值，精确到小数点后四位。

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Problem Description

Now, here is a fuction:
F(x) = 6 * x^7+8*x^6+7*x^3+5*x^2-y*x (0 <= x <=100)
Can you find the minimum value when x is between 0 and 100.

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 only one real numbers Y.(0 < Y <1e10)

Output

Just the minimum value (accurate up to 4 decimal places),when x is between 0 and 100.

Sample Input

Sample Output

  
   -74.4291
-178.8534

这个题要问的是最值问题，直接用的三分。

#if 0
#include<iostream>
#include<cmath> 
#include<iomanip>
using namespace std;
double x,y;
double fun(double x)
{
	double sum=(6.0*pow(x,7)+8.0*(pow(x,6))+7.0*pow(x,3)+5.0*pow(x,2)-y*x);
	return sum;
}

int main()
{
	int T;
	cin>>T;
	while(T--)
	{
		cin>>y;
		double mid,midmid,l=0,r=100;
		while(r-l>1.0e-6)
		{
			mid=(l+r)/2;
			midmid=(mid+r)/2;
			if(fun(mid)<fun(midmid)) //
			{
				r=midmid;
			}
			else
			{
				l=mid;
			}
		}
		
		cout<<fixed<<setprecision(4)<<fun(l)<<endl;
	}
		
}
#endif