题目链接：http://acm.hdu.edu.cn/showproblem.php?pid=3644

题意：给定n个点的一个多边形，一个圆的半径，判断圆是否可以放在多边形里，

由于圆形坐标没确定，所以采用模拟退火法来算，不断地减小步长，选取n个点，点在多边形内采用穿线法判断，

精度很坑爹，调了一下午精度，在wa与tle之间徘徊20+次，吐血AC。

代码：

/* ***********************************************
Author :rabbit
Created Time :2014/7/3 22:46:38
File Name :2.cpp
************************************************ */
#pragma comment(linker, "/STACK:102400000,102400000")
#include <stdio.h>
#include <iostream>
#include <algorithm>
#include <sstream>
#include <stdlib.h>
#include <string.h>
#include <limits.h>
#include <string>
#include <time.h>
#include <math.h>
#include <queue>
#include <stack>
#include <set>
#include <map>
using namespace std;
#define INF 0x3f3f3f3f
#define eps 1e-4
#define pi acos(-1.0)
typedef long long ll;
int dcmp(double x){
    if(fabs(x)<eps)return 0;
    return x>0?1:-1;
}
struct Point{
    double x,y;
    Point(double _x=0,double _y=0){
        x=_x;y=_y;
    }
};
Point operator + (Point a,Point b){
    return Point(a.x+b.x,a.y+b.y);
}
Point operator - (Point a, Point b){
    return Point(a.x-b.x,a.y-b.y);
}
Point operator * (Point a,double p){
    return  Point(a.x*p,a.y*p);
}
Point operator / (Point a,double p){
    return Point(a.x/p,a.y/p);
}
bool operator < (const Point &a,const Point &b){
    return a.x<b.x||(a.x==b.x&&a.y<b.y);
}
bool operator == (const Point &a,const Point &b){
    return dcmp(a.x-b.x)==0&&dcmp(a.y-b.y)==0;
}
double Dot(Point a, Point b){
    return a.x*b.x+a.y*b.y;
}
double Length(Point a){
    return sqrt(Dot(a,a));
}
double Angle(Point a,Point b){
    return acos(Dot(a,b)/Length(a)/Length(b));
}
double angle(Point a){
    return atan2(a.y,a.x);
}
double Cross(Point a,Point b){
    return a.x*b.y-a.y*b.x;
}
Point vecnit(Point x){
    return x/Length(x);
}
Point normal(Point x){
    return Point(-x.y,x.x)/Length(x);
}
Point Rotate(Point a,double rad){
    return Point(a.x*cos(rad)-a.y*sin(rad),a.x*sin(rad)+a.y*cos(rad));
}
Point GetLineIntersection(Point p,Point v,Point q,Point w){
    Point u=p-q;
    double t=Cross(w,u)/Cross(v,w);
    return p+v*t;
}
struct Line{
    Point p,v;
    double ang;
    Line(){};
    Line(Point _p,Point _v):p(_p),v(_v){
        ang=atan2(v.y,v.x);
    }
    Point point(double a){
        return p+(v*a);
    }
    bool operator < (const Line &L)const{
        return ang<L.ang;
    }
};
Point GetLineIntersection(Line a,Line b){
    return GetLineIntersection(a.p,a.v,b.p,b.v);
}
bool OnLeft(const Line &L,const Point &p){
    return Cross(L.v,p-L.p)>=0;
}
bool getdir(Point *p,int n){
    double ans=0;
    for(int i=0;i<n;i++)
        ans+=Cross(p[i],p[(i+1)%n]);
    if(dcmp(ans)>0)return 1;
    return 0;
}
bool OnSegment(Point p,Point a1,Point a2){
    return dcmp(Cross(a1-p,a2-p))==0&&dcmp(Dot(a1-p,a2-p))<=0;
}
double DistanceToSegment(Point p,Point a,Point b){
    if(a==b)return Length(p-a);
    Point v1=b-a,v2=p-a,v3=p-b;
    if(dcmp(Dot(v1,v2))<0)return Length(v2);
    else if(dcmp(Dot(v1,v3))>0)return Length(v3);
    else return fabs(Cross(v1,v2))/Length(v1);
}
int isPointInPolygon(Point p,Point *poly,int n){
    int wn=0;
    for(int i=0;i<n;i++){
        if(OnSegment(p,poly[i],poly[(i+1)%n]))return -1;
        int k=dcmp(Cross(poly[(i+1)%n]-poly[i],p-poly[i]));
        int d1=dcmp(poly[i].y-p.y);
        int d2=dcmp(poly[(i+1)%n].y-p.y);
        if(k>0&&d1<=0&&d2>0)wn++;
        if(k<0&&d2<=0&&d1>0)wn--;
    }
    if(wn!=0)return 1;
    return 0;
}
Point p[60],ret[60];
double ans[60];
int n;
double cal(Point tt){
    double ret=INF;
    for(int i=0;i<n;i++)
        ret=min(ret,DistanceToSegment(tt,p[i],p[(i+1)%n]));
    return ret;
}
int main()
{
     srand(time(NULL)); 
    while(~scanf("%d",&n)&&n){
        double maxx=-INF,minx=INF,maxy=-INF,miny=INF;
        for(int i=0;i<n;i++){
            scanf("%lf%lf",&p[i].x,&p[i].y);
            maxx=max(maxx,p[i].x);
            minx=min(minx,p[i].x);
            maxy=max(maxy,p[i].y);
            miny=min(miny,p[i].y);
        }
        double R;
        scanf("%lf",&R);
        bool flag=0;
        if(getdir(p,n)==0)reverse(p,p+n);
        maxx-=minx;maxy-=miny;
        double pp=sqrt(maxx*maxx+maxy*maxy)/2;
        p[n]=p[0];
        for(int i=0;i<n;i++)
            ret[i]=(p[i]+p[i+1])/2;
        memset(ans,0,sizeof(ans));
        while(!flag&&pp>1e-4){
            for(int i=0;!flag&&i<20;i++)
                for(int j=0;j<5&&!flag;j++){
                    double gg=rand();
                    Point temp;
                    temp.x=ret[i].x+pp*cos(gg);
                    temp.y=ret[i].y+pp*sin(gg);
                    if(isPointInPolygon(temp,p,n)){
                        double ss=cal(temp);
                        if(ss>ans[i]){
                            ans[i]=ss;
                            ret[i]=temp;
                            if(dcmp(ans[i]-R)>=0)flag=1;
                        }
                    }
                }
            pp*=0.8;
        }    
        if(flag)puts("Yes");
        else puts("No");
    }
}