HDU 3644 Simulated Annealing

Question link: http://acm.hdu.edu.cn/showproblem.php? PID = 1, 3644

Question: a polygon with N points, the radius of a circle, determines whether the circle can be placed in a polygon,

Because the circular coordinates are not determined, the simulated annealing method is used to calculate and continuously reduce the step size. N points are selected and points are determined by threading In the polygon,

Precision is very pitfall, tune an afternoon precision, between Wa and TLE lingers 20 + times, vomit blood AC.

Code:

/* ***********************************************Author :rabbitCreated Time :2014/7/3 22:46:38File 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");    }}