模拟退火 poj 1379

t

X Y n

求一个点  到n个点最短距离 最大

#include<stdio.h>
#include<algorithm>
#include<time.h>
#include<math.h>

using namespace std;
#define NUM 20
#define RAD 1000

class point
{
public:
    point(){}
    point(double xx,double yy)
    {
        this->x=xx;
        this->y=yy;
    }
    double x,y,val;
};
point p[10001],May[NUM];
int n;
double X,Y;
double dis(point a,point b)
{
    return sqrt((a.x-b.x)*(a.x-b.x)+(a.y-b.y)*(a.y-b.y));
}
double jud(point a)//求出最大的
{
    double len;
    len=1LL<<45;
    for(int i=0;i<n;i++)
        len=min(len,dis(a,p[i]));
    return len;
}
double Rand() //生成一个随机数
{
    return rand()%(RAD+1)/(1.0*RAD);
}
point Rand_point(point a,point b)  //这2个点之间随机的一个
{
    double x=a.x+(b.x-a.x)*Rand();
    double y=a.y+(b.y-a.y)*Rand();
    point tmp=point(x,y);
    tmp.val=jud(tmp);
    return tmp;
}
void solve(double D)
{
    May[0]=point(0,0);
    May[1]=point(X,0);
    May[2]=point(0,Y);
    May[3]=point(X,Y);  //4个特殊的点

    for(int i=4;i<NUM;i++)
        May[i]=Rand_point(May[0],May[3]);
    while(D>0.01)
    {
        for(int i=0;i<NUM;i++)
        {
            for(int j=0;j<NUM;j++) //每个点周围产生20个点
            {
                point tmp=Rand_point(point(max(0.0,May[i].x-D),max(0.0,May[i].y-D)),point(min(X,May[i].x+D),min(Y,May[i].y+D)));
                if(tmp.val>May[i].val)
                    May[i]=tmp;
            }
        }
        D*=0.9;
    }
    point ans;
    ans.val=0;
    for(int i=0;i<NUM;i++)
        if(May[i].val>ans.val)
            ans=May[i];
    printf("The safest point is (%.1lf, %.1lf).
",ans.x,ans.y);
}
int main()
{
    int t;
    scanf("%d",&t);
    while(t--)
    {
        scanf("%lf%lf%d",&X,&Y,&n);
        for(int i=0;i<n;i++)
            scanf("%lf%lf",&p[i].x,&p[i].y);
        solve(max(X,Y));
    }
    return 0;
}