[数据结构与算法]模拟退火算法模板与HDUOJ2899

模拟退火算法

模拟退火简易模板

double solve(){
	double T=100; //初始温度
	double delta = 0.98; //降温系数
	double x=50.0;  //x的初始温度
	double now=func(x);  //计算初始函数值
	double ans=now;  //返回值
	while(T>eps){     //eps是终止温度
		int f[2]={1,-1};
		double newx = x+f[rand()%2]*T; //按概率改变x，随T的降温而减少
		if(newx >= 0 && newx<=100){
			double next = func(newx);
			ans=min(ans,next);
			if(now-next>eps){x=newx;now=next;}			
		}
		T*=delta;
	}
	return ans;
}

例题（HDUOJ2899）：“Strange function”

#include<iostream>
#include<algorithm>
#include<cstring>
#include<string.h>
#include<cstdio>

using namespace std; 

const double eps = 1e-8;
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)-y*x;
}

double solve(){
	double T=100; //初始温度
	double delta = 0.98; //降温系数
	double x=50.0;  //x的初始温度
	double now=func(x);  //计算初始函数值
	double ans=now;  //返回值
	while(T>eps){     //eps是终止温度
		int f[2]={1,-1};
		double newx = x+f[rand()%2]*T; //按概率改变x，随T的降温而减少
		if(newx >= 0 && newx<=100){
			double next = func(newx);
			ans=min(ans,next);
			if(now-next>eps){x=newx;now=next;}			
		}
		T*=delta;
	}
	return ans;
}

int main(){
	int cas;scanf("%d",&cas);
	while(cas--){
		scanf("%lf",&y);
		printf("%.4lf\n",solve());
	}	
	return 0;
}