A Star not a Tree?

版权声明：本文为博主原创文章，未经博主允许不得转载。 https://blog.csdn.net/leekerian/article/details/82263457

第一道模拟退火

#include <iostream>
#include <cmath>
#include <cstdio>
#include <algorithm>

using namespace std;

const int maxn=111;

struct Point
{
    double x,y;
    Point(){}
    Point(double _x,double _y)
    {
        x=_x;
        y=_y;
    }
    Point operator -(const Point &b)const
    {
        return Point(x-b.x,y-b.y);
    }
    double operator ^(const Point &b)const
    {
        return x*b.y-y*b.x;
    }
    double operator *(const Point &b)const
    {
        return x*b.x+y*b.y;
    }
};

Point p[maxn];


int mx[4]={0,0,1,-1};
int my[4]={1,-1,0,0};
const double eps=1e-8;//终点温度
double  T=100;//启示温度
const double delta=0.98;//温度下降梯度


int sgn(double x)
{
    if(fabs(x)<eps)
        return 0;
    if(x<0)
        return -1;
    else
        return 1;
}



double dist(Point a,Point b)
{
    return sqrt((a-b)*(a-b));
}


double get_ans(int n,Point s)
{
    double ans=0;
    for(int i=0;i<n;i++)
        ans+=dist(p[i],s);
    return ans;
}
double search_(int n)
{
    Point s=p[0];//qidian
    double ans=1e99;
    while(T>eps)
    {
        bool flag=1;
        while(flag)
        {
            flag=0;
            for(int i=0;i<4;i++)
            {
                Point t;
                t=s;
                t.x=t.x+mx[i]*T;
                t.y=t.y+my[i]*T;
                double ans1=get_ans(n,t);
                if(ans1<ans)
                {
                    s=t;
                    flag=1;
                    ans=ans1;
                }
            }
        }
        T=T*delta;
    }
    return ans;
}
int main()
{
    int n;
    while(scanf("%d",&n)!=EOF)
    {
        for(int i=0;i<n;i++)
            scanf("%lf %lf",&p[i].x,&p[i].y);
        printf("%.0lf\n",search_(n));
    }
    return 0;
}