地址:http://acm.hdu.edu.cn/showproblem.php?pid=2899
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.
#include<bits/stdc++.h>
#include<iostream>
#include<cstring>
#include<cmath>
#include<cstdlib>
#include<stack>
#include<queue>
#include<cstdio>
#include<vector>
#include<algorithm>
using namespace std;
typedef long long ll;
const double eps=1e-8; //终止温度
double y;
double func(double x)
{
return 6*pow(x,7.0)+8*pow(x,6.0)+7*pow(x,3.0)+5*pow(x,2.0)-x*y;
}
double solve()
{
double T=100; //初始温度
double delta=0.98;//降温系数
double x=50.0; //x的初始值
double now=func(x); //初始函数值
double ans=now; //记录结果
while(T>eps)
{
int f[2]={1,-1};
double newx=x+f[rand()%2]*T; //按概率改变x
if(newx>=0&&newx<=100)
{
double next=func(newx);
ans=min(ans,next);
if(now-next>eps)
{
x=newx;
now=next;
}
// cout<<x<<endl;
}
T*=delta;
}
return ans;
}
int main()
{
int t;
scanf("%d",&t);
while(t--)
{
scanf("%lf",&y);
printf("%.4lf\n",solve());
}
}