HRBUST 2024 Strange fuction || HDU 2899 Strange fuction

Sol:求函数的最小值。求两次导数，判断函数的单调性和凹凸性即可，用二分查找即可。

#include <cstdio>
#include <cmath>

using namespace std;

const double eps = 1e-10;
int T;
double y;

double G(double x)
{
	return 42*pow(x,6)+48*pow(x,5)+21*pow(x,2)+10*x-y;
}
double F(double x)
{
	return 6*pow(x,7)+8*pow(x,6)+7*pow(x,3)+5*pow(x,2)-y*x;
}

int main()
{
	scanf("%d",&T);
	while(T--)
	{
		scanf("%lf",&y);
		if(G(100.0)<=0)
		{
			printf("%.4lf\n",F(100.0));
		}
		else
		{
			double L=0,R=100,mid;
			while(R-L>=eps)
			{
				mid=(L+R)/2.0;
				if(G(mid)<0)
					L=mid;
				else
					R=mid;
			}
			printf("%.4lf\n",F(mid));
		}
	}
	return 0;
}

HRBUST 2024 Strange fuction || HDU 2899 Strange fuction

原文：http://blog.csdn.net/imutzcy/article/details/18913053