• 戴牛一万行的几何模板



    #include<vector>
    #include<list>
    #include<map>
    #include<set>
    #include<deque>
    #include<queue>
    #include<stack>
    #include<bitset>
    #include<algorithm>
    #include<functional>
    #include<numeric>
    #include<utility>
    #include<iostream>
    #include<sstream>
    #include<iomanip>
    #include<cstdio>
    #include<cmath>
    #include<cstdlib>
    #include<cctype>
    #include<string>
    #include<cstring>
    #include<cstdio>
    #include<cmath>
    #include<cstdlib>
    #include<ctime>
    #include<climits>
    #include<complex>
    #define mp make_pair
    #define pb push_back
    using namespace std;
    const double eps=1e-8;
    const double pi=acos(-1.0);
    const double inf=1e20;
    const int maxp=1111;
    int dblcmp(double d)
    {
        if (fabs(d)<eps)return 0;
        return d>eps?1:-1;
    }
    inline double sqr(double x){return x*x;}
    struct point
    {
        double x,y;
        point(){}
        point(double _x,double _y):
        x(_x),y(_y){};
        void input()
        {
            scanf("%lf%lf",&x,&y);
        }
        void output()
        {
            printf("%.2f %.2f\n",x,y);
        }
        bool operator==(point a)const
        {
            return dblcmp(a.x-x)==0&&dblcmp(a.y-y)==0;
        }
        bool operator<(point a)const
        {
            return dblcmp(a.x-x)==0?dblcmp(y-a.y)<0:x<a.x;
        }
        double len()
        {
            return hypot(x,y);
        }
        double len2()
        {
            return x*x+y*y;
        }
        double distance(point p)
        {
            return hypot(x-p.x,y-p.y);
        }
        point add(point p)
        {
            return point(x+p.x,y+p.y);
        }
        point sub(point p)
        {
            return point(x-p.x,y-p.y);
        }
        point mul(double b)
        {
            return point(x*b,y*b);
        }
        point div(double b)
        {
            return point(x/b,y/b);
        }
        double dot(point p)
        {
            return x*p.x+y*p.y;
        }
        double det(point p)
        {
            return x*p.y-y*p.x;
        }
        double rad(point a,point b)
        {
            point p=*this;
            return fabs(atan2(fabs(a.sub(p).det(b.sub(p))),a.sub(p).dot(b.sub(p))));
        }
        point trunc(double r)
        {
            double l=len();
            if (!dblcmp(l))return *this;
            r/=l;
            return point(x*r,y*r);
        }
        point rotleft()
        {
            return point(-y,x);
        }
        point rotright()
        {
            return point(y,-x);
        }
        point rotate(point p,double angle)//绕点p逆时针旋转angle角度
        {
            point v=this->sub(p);
            double c=cos(angle),s=sin(angle);
            return point(p.x+v.x*c-v.y*s,p.y+v.x*s+v.y*c);
        }
    };
    struct line
    {
        point a,b;
        line(){}
        line(point _a,point _b)
        {
            a=_a;
            b=_b;
        }
        bool operator==(line v)
        {
            return (a==v.a)&&(b==v.b);
        }
        //倾斜角angle
        line(point p,double angle)
        {
            a=p;
            if (dblcmp(angle-pi/2)==0)
            {
                b=a.add(point(0,1));
            }
            else
            {
                b=a.add(point(1,tan(angle)));
            }
        }
        //ax+by+c=0
        line(double _a,double _b,double _c)
        {
            if (dblcmp(_a)==0)
            {
                a=point(0,-_c/_b);
                b=point(1,-_c/_b);
            }
            else if (dblcmp(_b)==0)
            {
                a=point(-_c/_a,0);
                b=point(-_c/_a,1);
            }
            else
            {
                a=point(0,-_c/_b);
                b=point(1,(-_c-_a)/_b);
            }
        }
        void input()
        {
            a.input();
            b.input();
        }
        void adjust()
        {
            if (b<a)swap(a,b);
        }
        double length()
        {
            return a.distance(b);
        }
        double angle()//直线倾斜角 0<=angle<180
        {
            double k=atan2(b.y-a.y,b.x-a.x);
            if (dblcmp(k)<0)k+=pi;
            if (dblcmp(k-pi)==0)k-=pi;
            return k;
        }
        //点和线段关系
        //1 在逆时针
        //2 在顺时针
        //3 平行
        int relation(point p)
        {
            int c=dblcmp(p.sub(a).det(b.sub(a)));
            if (c<0)return 1;
            if (c>0)return 2;
            return 3;
        }
        bool pointonseg(point p)
        {
            return dblcmp(p.sub(a).det(b.sub(a)))==0&&dblcmp(p.sub(a).dot(p.sub(b)))<=0;
        }
        bool parallel(line v)
        {
            return dblcmp(b.sub(a).det(v.b.sub(v.a)))==0;
        }
        //2 规范相交
        //1 非规范相交
        //0 不相交
        int segcrossseg(line v)
        {
            int d1=dblcmp(b.sub(a).det(v.a.sub(a)));
            int d2=dblcmp(b.sub(a).det(v.b.sub(a)));
            int d3=dblcmp(v.b.sub(v.a).det(a.sub(v.a)));
            int d4=dblcmp(v.b.sub(v.a).det(b.sub(v.a)));
            if ((d1^d2)==-2&&(d3^d4)==-2)return 2;
            return (d1==0&&dblcmp(v.a.sub(a).dot(v.a.sub(b)))<=0||
                    d2==0&&dblcmp(v.b.sub(a).dot(v.b.sub(b)))<=0||
                    d3==0&&dblcmp(a.sub(v.a).dot(a.sub(v.b)))<=0||
                    d4==0&&dblcmp(b.sub(v.a).dot(b.sub(v.b)))<=0);
        }
        int linecrossseg(line v)//*this seg v line
        {
            int d1=dblcmp(b.sub(a).det(v.a.sub(a)));
            int d2=dblcmp(b.sub(a).det(v.b.sub(a)));
            if ((d1^d2)==-2)return 2;
            return (d1==0||d2==0);
        }
        //0 平行
        //1 重合
        //2 相交
        int linecrossline(line v)
        {
            if ((*this).parallel(v))
            {
                return v.relation(a)==3;
            }
            return 2;
        }
        point crosspoint(line v)
        {
            double a1=v.b.sub(v.a).det(a.sub(v.a));
            double a2=v.b.sub(v.a).det(b.sub(v.a));
            return point((a.x*a2-b.x*a1)/(a2-a1),(a.y*a2-b.y*a1)/(a2-a1));
        }
        double dispointtoline(point p)
        {
            return fabs(p.sub(a).det(b.sub(a)))/length();
        }
        double dispointtoseg(point p)
        {
            if (dblcmp(p.sub(b).dot(a.sub(b)))<0||dblcmp(p.sub(a).dot(b.sub(a)))<0)
            {
                return min(p.distance(a),p.distance(b));
            }
            return dispointtoline(p);
        }
        point lineprog(point p)
        {
            return a.add(b.sub(a).mul(b.sub(a).dot(p.sub(a))/b.sub(a).len2()));
        }
        point symmetrypoint(point p)
        {
            point q=lineprog(p);
            return point(2*q.x-p.x,2*q.y-p.y);
        }
    };
    struct circle
    {
        point p;
        double r;
        circle(){}
        circle(point _p,double _r):
        p(_p),r(_r){};
        circle(double x,double y,double _r):
        p(point(x,y)),r(_r){};
        circle(point a,point b,point c)//三角形的外接圆
        {
            p=line(a.add(b).div(2),a.add(b).div(2).add(b.sub(a).rotleft())).crosspoint(line(c.add(b).div(2),c.add(b).div(2).add(b.sub(c).rotleft())));
            r=p.distance(a);
        }
        circle(point a,point b,point c,bool t)//三角形的内切圆
        {
            line u,v;
            double m=atan2(b.y-a.y,b.x-a.x),n=atan2(c.y-a.y,c.x-a.x);
            u.a=a;
            u.b=u.a.add(point(cos((n+m)/2),sin((n+m)/2)));
            v.a=b;
            m=atan2(a.y-b.y,a.x-b.x),n=atan2(c.y-b.y,c.x-b.x);
            v.b=v.a.add(point(cos((n+m)/2),sin((n+m)/2)));
            p=u.crosspoint(v);
            r=line(a,b).dispointtoseg(p);
        }
        void input()
        {
            p.input();
            scanf("%lf",&r);
        }
        void output()
        {
            printf("%.2lf %.2lf %.2lf\n",p.x,p.y,r);
        }
        bool operator==(circle v)
        {
            return ((p==v.p)&&dblcmp(r-v.r)==0);
        }
        bool operator<(circle v)const
        {
            return ((p<v.p)||(p==v.p)&&dblcmp(r-v.r)<0);
        }
        double area()
        {
            return pi*sqr(r);
        }
        double circumference()
        {
            return 2*pi*r;
        }
        //0 圆外
        //1 圆上
        //2 圆内
        int relation(point b)
        {
            double dst=b.distance(p);
            if (dblcmp(dst-r)<0)return 2;
            if (dblcmp(dst-r)==0)return 1;
            return 0;
        }
        int relationseg(line v)
        {
            double dst=v.dispointtoseg(p);
            if (dblcmp(dst-r)<0)return 2;
            if (dblcmp(dst-r)==0)return 1;
            return 0;
        }
        int relationline(line v)
        {
            double dst=v.dispointtoline(p);
            if (dblcmp(dst-r)<0)return 2;
            if (dblcmp(dst-r)==0)return 1;
            return 0;
        }
        //过a b两点 半径r的两个圆
        int getcircle(point a,point b,double r,circle&c1,circle&c2)
        {
            circle x(a,r),y(b,r);
            int t=x.pointcrosscircle(y,c1.p,c2.p);
            if (!t)return 0;
            c1.r=c2.r=r;
            return t;
        }
        //与直线u相切 过点q 半径r1的圆
        int getcircle(line u,point q,double r1,circle &c1,circle &c2)
        {
            double dis=u.dispointtoline(q);
            if (dblcmp(dis-r1*2)>0)return 0;
            if (dblcmp(dis)==0)
            {
                c1.p=q.add(u.b.sub(u.a).rotleft().trunc(r1));
                c2.p=q.add(u.b.sub(u.a).rotright().trunc(r1));
                c1.r=c2.r=r1;
                return 2;
            }
            line u1=line(u.a.add(u.b.sub(u.a).rotleft().trunc(r1)),u.b.add(u.b.sub(u.a).rotleft().trunc(r1)));
            line u2=line(u.a.add(u.b.sub(u.a).rotright().trunc(r1)),u.b.add(u.b.sub(u.a).rotright().trunc(r1)));
            circle cc=circle(q,r1);
            point p1,p2;
            if (!cc.pointcrossline(u1,p1,p2))cc.pointcrossline(u2,p1,p2);
            c1=circle(p1,r1);
            if (p1==p2)
            {
                c2=c1;return 1;
            }
            c2=circle(p2,r1);
            return 2;
        }
        //同时与直线u,v相切 半径r1的圆
        int getcircle(line u,line v,double r1,circle &c1,circle &c2,circle &c3,circle &c4)
        {
            if (u.parallel(v))return 0;
            line u1=line(u.a.add(u.b.sub(u.a).rotleft().trunc(r1)),u.b.add(u.b.sub(u.a).rotleft().trunc(r1)));
            line u2=line(u.a.add(u.b.sub(u.a).rotright().trunc(r1)),u.b.add(u.b.sub(u.a).rotright().trunc(r1)));
            line v1=line(v.a.add(v.b.sub(v.a).rotleft().trunc(r1)),v.b.add(v.b.sub(v.a).rotleft().trunc(r1)));
            line v2=line(v.a.add(v.b.sub(v.a).rotright().trunc(r1)),v.b.add(v.b.sub(v.a).rotright().trunc(r1)));
            c1.r=c2.r=c3.r=c4.r=r1;
            c1.p=u1.crosspoint(v1);
            c2.p=u1.crosspoint(v2);
            c3.p=u2.crosspoint(v1);
            c4.p=u2.crosspoint(v2);
            return 4;
        }
        //同时与不相交圆cx,cy相切 半径为r1的圆
        int getcircle(circle cx,circle cy,double r1,circle&c1,circle&c2)
        {
            circle x(cx.p,r1+cx.r),y(cy.p,r1+cy.r);
            int t=x.pointcrosscircle(y,c1.p,c2.p);
            if (!t)return 0;
            c1.r=c2.r=r1;
            return t;
        }
        int pointcrossline(line v,point &p1,point &p2)//求与线段交要先判断relationseg
        {
            if (!(*this).relationline(v))return 0;
            point a=v.lineprog(p);
            double d=v.dispointtoline(p);
            d=sqrt(r*r-d*d);
            if (dblcmp(d)==0)
            {
                p1=a;
                p2=a;
                return 1;
            }
            p1=a.sub(v.b.sub(v.a).trunc(d));
            p2=a.add(v.b.sub(v.a).trunc(d));
            return 2;
        }
        //5 相离
        //4 外切
        //3 相交
        //2 内切
        //1 内含
        int relationcircle(circle v)
        {
            double d=p.distance(v.p);
            if (dblcmp(d-r-v.r)>0)return 5;
            if (dblcmp(d-r-v.r)==0)return 4;
            double l=fabs(r-v.r);
            if (dblcmp(d-r-v.r)<0&&dblcmp(d-l)>0)return 3;
            if (dblcmp(d-l)==0)return 2;
            if (dblcmp(d-l)<0)return 1;
        }
        int pointcrosscircle(circle v,point &p1,point &p2)
        {
            int rel=relationcircle(v);
            if (rel==1||rel==5)return 0;
            double d=p.distance(v.p);
            double l=(d+(sqr(r)-sqr(v.r))/d)/2;
            double h=sqrt(sqr(r)-sqr(l));
            p1=p.add(v.p.sub(p).trunc(l).add(v.p.sub(p).rotleft().trunc(h)));
            p2=p.add(v.p.sub(p).trunc(l).add(v.p.sub(p).rotright().trunc(h)));
            if (rel==2||rel==4)
            {
                return 1;
            }
            return 2;
        }
        //过一点做圆的切线 (先判断点和圆关系)
        int tangentline(point q,line &u,line &v)
        {
            int x=relation(q);
            if (x==2)return 0;
            if (x==1)
            {
                u=line(q,q.add(q.sub(p).rotleft()));
                v=u;
                return 1;
            }
            double d=p.distance(q);
            double l=sqr(r)/d;
            double h=sqrt(sqr(r)-sqr(l));
            u=line(q,p.add(q.sub(p).trunc(l).add(q.sub(p).rotleft().trunc(h))));
            v=line(q,p.add(q.sub(p).trunc(l).add(q.sub(p).rotright().trunc(h))));
            return 2;
        }
        double areacircle(circle v)
        {
            int rel=relationcircle(v);
            if (rel>=4)return 0.0;
            if (rel<=2)return min(area(),v.area());
            double d=p.distance(v.p);
            double hf=(r+v.r+d)/2.0;
            double ss=2*sqrt(hf*(hf-r)*(hf-v.r)*(hf-d));
            double a1=acos((r*r+d*d-v.r*v.r)/(2.0*r*d));
            a1=a1*r*r;
            double a2=acos((v.r*v.r+d*d-r*r)/(2.0*v.r*d));
            a2=a2*v.r*v.r;
            return a1+a2-ss;
        }
        double areatriangle(point a,point b)
        {
            if (dblcmp(p.sub(a).det(p.sub(b))==0))return 0.0;
            point q[5];
            int len=0;
            q[len++]=a;
            line l(a,b);
            point p1,p2;
            if (pointcrossline(l,q[1],q[2])==2)
            {
                if (dblcmp(a.sub(q[1]).dot(b.sub(q[1])))<0)q[len++]=q[1];
                if (dblcmp(a.sub(q[2]).dot(b.sub(q[2])))<0)q[len++]=q[2];
            }
            q[len++]=b;
            if (len==4&&(dblcmp(q[0].sub(q[1]).dot(q[2].sub(q[1])))>0))swap(q[1],q[2]);
            double res=0;
            int i;
            for (i=0;i<len-1;i++)
            {
                if (relation(q[i])==0||relation(q[i+1])==0)
                {
                    double arg=p.rad(q[i],q[i+1]);
                    res+=r*r*arg/2.0;
                }
                else
                {
                    res+=fabs(q[i].sub(p).det(q[i+1].sub(p))/2.0);
                }
            }
            return res;
        }
    };
    struct polygon
    {
        int n;
        point p[maxp];
        line l[maxp];
        void input()
        {
            n=4;
            for (int i=0;i<n;i++)
            {
                p[i].input();
            }
        }
        void add(point q)
        {
            p[n++]=q;
        }
        void getline()
        {
            for (int i=0;i<n;i++)
            {
                l[i]=line(p[i],p[(i+1)%n]);
            }
        }
        struct cmp
        {
            point p;
            cmp(const point &p0){p=p0;}
            bool operator()(const point &aa,const point &bb)
            {
                point a=aa,b=bb;
                int d=dblcmp(a.sub(p).det(b.sub(p)));
                if (d==0)
                {
                    return dblcmp(a.distance(p)-b.distance(p))<0;
                }
                return d>0;
            }
        };
        void norm()
        {
            point mi=p[0];
            for (int i=1;i<n;i++)mi=min(mi,p[i]);
            sort(p,p+n,cmp(mi));
        }
        void getconvex(polygon &convex)
        {
            int i,j,k;
            sort(p,p+n);
            convex.n=n;
            for (i=0;i<min(n,2);i++)
            {
                convex.p[i]=p[i];
            }
            if (n<=2)return;
            int &top=convex.n;
            top=1;
            for (i=2;i<n;i++)
            {
                while (top&&convex.p[top].sub(p[i]).det(convex.p[top-1].sub(p[i]))<=0)
                    top--;
                convex.p[++top]=p[i];
            }
            int temp=top;
            convex.p[++top]=p[n-2];
            for (i=n-3;i>=0;i--)
            {
                while (top!=temp&&convex.p[top].sub(p[i]).det(convex.p[top-1].sub(p[i]))<=0)
                    top--;
                convex.p[++top]=p[i];
            }
        }
        bool isconvex()
        {
            bool s[3];
            memset(s,0,sizeof(s));
            int i,j,k;
            for (i=0;i<n;i++)
            {
                j=(i+1)%n;
                k=(j+1)%n;
                s[dblcmp(p[j].sub(p[i]).det(p[k].sub(p[i])))+1]=1;
                if (s[0]&&s[2])return 0;
            }
            return 1;
        }
        //3 点上
        //2 边上
        //1 内部
        //0 外部
        int relationpoint(point q)
        {
            int i,j;
            for (i=0;i<n;i++)
            {
                if (p[i]==q)return 3;
            }
            getline();
            for (i=0;i<n;i++)
            {
                if (l[i].pointonseg(q))return 2;
            }
            int cnt=0;
            for (i=0;i<n;i++)
            {
                j=(i+1)%n;
                int k=dblcmp(q.sub(p[j]).det(p[i].sub(p[j])));
                int u=dblcmp(p[i].y-q.y);
                int v=dblcmp(p[j].y-q.y);
                if (k>0&&u<0&&v>=0)cnt++;
                if (k<0&&v<0&&u>=0)cnt--;
            }
            return cnt!=0;
        }
        //1 在多边形内长度为正
        //2 相交或与边平行
        //0 无任何交点
        int relationline(line u)
        {
            int i,j,k=0;
            getline();
            for (i=0;i<n;i++)
            {
                if (l[i].segcrossseg(u)==2)return 1;
                if (l[i].segcrossseg(u)==1)k=1;
            }
            if (!k)return 0;
            vector<point>vp;
            for (i=0;i<n;i++)
            {
                if (l[i].segcrossseg(u))
                {
                    if (l[i].parallel(u))
                    {
                        vp.pb(u.a);
                        vp.pb(u.b);
                        vp.pb(l[i].a);
                        vp.pb(l[i].b);
                        continue;
                    }
                    vp.pb(l[i].crosspoint(u));
                }
            }
            sort(vp.begin(),vp.end());
            int sz=vp.size();
            for (i=0;i<sz-1;i++)
            {
                point mid=vp[i].add(vp[i+1]).div(2);
                if (relationpoint(mid)==1)return 1;
            }
            return 2;
        }
        //直线u切割凸多边形左侧
        //注意直线方向
        void convexcut(line u,polygon &po)
        {
            int i,j,k;
            int &top=po.n;
            top=0;
            for (i=0;i<n;i++)
            {
                int d1=dblcmp(p[i].sub(u.a).det(u.b.sub(u.a)));
                int d2=dblcmp(p[(i+1)%n].sub(u.a).det(u.b.sub(u.a)));
                if (d1>=0)po.p[top++]=p[i];
                if (d1*d2<0)po.p[top++]=u.crosspoint(line(p[i],p[(i+1)%n]));
            }
        }
        double getcircumference()
        {
            double sum=0;
            int i;
            for (i=0;i<n;i++)
            {
                sum+=p[i].distance(p[(i+1)%n]);
            }
            return sum;
        }
        double getarea()
        {
            double sum=0;
            int i;
            for (i=0;i<n;i++)
            {
                sum+=p[i].det(p[(i+1)%n]);
            }
            return fabs(sum)/2;
        }
        bool getdir()//1代表逆时针 0代表顺时针
        {
            double sum=0;
            int i;
            for (i=0;i<n;i++)
            {
                sum+=p[i].det(p[(i+1)%n]);
            }
            if (dblcmp(sum)>0)return 1;
            return 0;
        }
        point getbarycentre()
        {
            point ret(0,0);
            double area=0;
            int i;
            for (i=1;i<n-1;i++)
            {
                double tmp=p[i].sub(p[0]).det(p[i+1].sub(p[0]));
                if (dblcmp(tmp)==0)continue;
                area+=tmp;
                ret.x+=(p[0].x+p[i].x+p[i+1].x)/3*tmp;
                ret.y+=(p[0].y+p[i].y+p[i+1].y)/3*tmp;
            }
            if (dblcmp(area))ret=ret.div(area);
            return ret;
        }
        double areaintersection(polygon po)
        {
        }
        double areaunion(polygon po)
        {
            return getarea()+po.getarea()-areaintersection(po);
        }
        double areacircle(circle c)
        {
            int i,j,k,l,m;
            double ans=0;
            for (i=0;i<n;i++)
            {
                int j=(i+1)%n;
                if (dblcmp(p[j].sub(c.p).det(p[i].sub(c.p)))>=0)
                {
                    ans+=c.areatriangle(p[i],p[j]);
                }
                else
                {
                    ans-=c.areatriangle(p[i],p[j]);
                }
            }
            return fabs(ans);
        }
        //多边形和圆关系
        //0 一部分在圆外
        //1 与圆某条边相切
        //2 完全在圆内
        int relationcircle(circle c)
        {
            getline();
            int i,x=2;
            if (relationpoint(c.p)!=1)return 0;
            for (i=0;i<n;i++)
            {
                if (c.relationseg(l[i])==2)return 0;
                if (c.relationseg(l[i])==1)x=1;
            }
            return x;
        }
        void find(int st,point tri[],circle &c)
        {
            if (!st)
            {
                c=circle(point(0,0),-2);
            }
            if (st==1)
            {
                c=circle(tri[0],0);
            }
            if (st==2)
            {
                c=circle(tri[0].add(tri[1]).div(2),tri[0].distance(tri[1])/2.0);
            }
            if (st==3)
            {
                c=circle(tri[0],tri[1],tri[2]);
            }
        }
        void solve(int cur,int st,point tri[],circle &c)
        {
            find(st,tri,c);
            if (st==3)return;
            int i;
            for (i=0;i<cur;i++)
            {
                if (dblcmp(p[i].distance(c.p)-c.r)>0)
                {
                    tri[st]=p[i];
                    solve(i,st+1,tri,c);
                }
            }
        }
        circle mincircle()//点集最小圆覆盖
        {
            random_shuffle(p,p+n);
            point tri[4];
            circle c;
            solve(n,0,tri,c);
            return c;
        }
        int circlecover(double r)//单位圆覆盖
        {
            int ans=0,i,j;
            vector<pair<double,int> >v;
            for (i=0;i<n;i++)
            {
                v.clear();
                for (j=0;j<n;j++)if (i!=j)
                {
                    point q=p[i].sub(p[j]);
                    double d=q.len();
                    if (dblcmp(d-2*r)<=0)
                    {
                        double arg=atan2(q.y,q.x);
                        if (dblcmp(arg)<0)arg+=2*pi;
                        double t=acos(d/(2*r));
                        v.push_back(make_pair(arg-t+2*pi,-1));
                        v.push_back(make_pair(arg+t+2*pi,1));
                    }
                }
                sort(v.begin(),v.end());
                int cur=0;
                for (j=0;j<v.size();j++)
                {
                    if (v[j].second==-1)++cur;
                    else --cur;
                    ans=max(ans,cur);
                }
            }
            return ans+1;
        }
        int pointinpolygon(point q)//点在凸多边形内部的判定
        {
            if (getdir())reverse(p,p+n);
            if (dblcmp(q.sub(p[0]).det(p[n-1].sub(p[0])))==0)
            {
                if (line(p[n-1],p[0]).pointonseg(q))return n-1;
                return -1;
            }
            int low=1,high=n-2,mid;
            while (low<=high)
            {
                mid=(low+high)>>1;
                if (dblcmp(q.sub(p[0]).det(p[mid].sub(p[0])))>=0&&dblcmp(q.sub(p[0]).det(p[mid+1].sub(p[0])))<0)
                {
                    polygon c;
                    c.p[0]=p[mid];
                    c.p[1]=p[mid+1];
                    c.p[2]=p[0];
                    c.n=3;
                    if (c.relationpoint(q))return mid;
                    return -1;
                }
                if (dblcmp(q.sub(p[0]).det(p[mid].sub(p[0])))>0)
                {
                    low=mid+1;
                }
                else
                {
                    high=mid-1;
                }
            }
            return -1;
        }
    };
    struct polygons
    {
        vector<polygon>p;
        polygons()
        {
            p.clear();
        }
        void clear()
        {
            p.clear();
        }
        void push(polygon q)
        {
            if (dblcmp(q.getarea()))p.pb(q);
        }
        vector<pair<double,int> >e;
        void ins(point s,point t,point X,int i)
        {
            double r=fabs(t.x-s.x)>eps?(X.x-s.x)/(t.x-s.x):(X.y-s.y)/(t.y-s.y);
            r=min(r,1.0);r=max(r,0.0);
            e.pb(mp(r,i));
        }
        double polyareaunion()
        {
            double ans=0.0;
            int c0,c1,c2,i,j,k,w;
            for (i=0;i<p.size();i++)
            {
                if (p[i].getdir()==0)reverse(p[i].p,p[i].p+p[i].n);
            }
            for (i=0;i<p.size();i++)
            {
                for (k=0;k<p[i].n;k++)
                {
                    point &s=p[i].p[k],&t=p[i].p[(k+1)%p[i].n];
                    if (!dblcmp(s.det(t)))continue;
                    e.clear();
                    e.pb(mp(0.0,1));
                    e.pb(mp(1.0,-1));
                    for (j=0;j<p.size();j++)if (i!=j)
                    {
                        for (w=0;w<p[j].n;w++)
                        {
                            point a=p[j].p[w],b=p[j].p[(w+1)%p[j].n],c=p[j].p[(w-1+p[j].n)%p[j].n];
                            c0=dblcmp(t.sub(s).det(c.sub(s)));
                            c1=dblcmp(t.sub(s).det(a.sub(s)));
                            c2=dblcmp(t.sub(s).det(b.sub(s)));
                            if (c1*c2<0)ins(s,t,line(s,t).crosspoint(line(a,b)),-c2);
                            else if (!c1&&c0*c2<0)ins(s,t,a,-c2);
                            else if (!c1&&!c2)
                            {
                                int c3=dblcmp(t.sub(s).det(p[j].p[(w+2)%p[j].n].sub(s)));
                                int dp=dblcmp(t.sub(s).dot(b.sub(a)));
                                if (dp&&c0)ins(s,t,a,dp>0?c0*((j>i)^(c0<0)):-(c0<0));
                                if (dp&&c3)ins(s,t,b,dp>0?-c3*((j>i)^(c3<0)):c3<0);
                            }
                        }
                    }
                    sort(e.begin(),e.end());
                    int ct=0;
                    double tot=0.0,last;
                    for (j=0;j<e.size();j++)
                    {
                        if (ct==2)tot+=e[j].first-last;
                        ct+=e[j].second;
                        last=e[j].first;
                    }
                    ans+=s.det(t)*tot;
                }
            }
            return fabs(ans)*0.5;
        }
    };
    const int maxn=500;
    struct circles
    {
        circle c[maxn];
        double ans[maxn];//ans[i]表示被覆盖了i次的面积
        double pre[maxn];
        int n;
        circles(){}
        void add(circle cc)
        {
            c[n++]=cc;
        }
        bool inner(circle x,circle y)
        {
            if (x.relationcircle(y)!=1)return 0;
            return dblcmp(x.r-y.r)<=0?1:0;
        }
        void init_or()//圆的面积并去掉内含的圆
        {
            int i,j,k=0;
            bool mark[maxn]={0};
            for (i=0;i<n;i++)
            {
                for (j=0;j<n;j++)if (i!=j&&!mark[j])
                {
                    if ((c[i]==c[j])||inner(c[i],c[j]))break;
                }
                if (j<n)mark[i]=1;
            }
            for (i=0;i<n;i++)if (!mark[i])c[k++]=c[i];
            n=k;
        }
        void init_and()//圆的面积交去掉内含的圆
        {
            int i,j,k=0;
            bool mark[maxn]={0};
            for (i=0;i<n;i++)
            {
                for (j=0;j<n;j++)if (i!=j&&!mark[j])
                {
                    if ((c[i]==c[j])||inner(c[j],c[i]))break;
                }
                if (j<n)mark[i]=1;
            }
            for (i=0;i<n;i++)if (!mark[i])c[k++]=c[i];
            n=k;
        }
        double areaarc(double th,double r)
        {
            return 0.5*sqr(r)*(th-sin(th));
        }
        void getarea()
        {
            int i,j,k;
            memset(ans,0,sizeof(ans));
            vector<pair<double,int> >v;
            for (i=0;i<n;i++)
            {
                v.clear();
                v.push_back(make_pair(-pi,1));
                v.push_back(make_pair(pi,-1));
                for (j=0;j<n;j++)if (i!=j)
                {
                    point q=c[j].p.sub(c[i].p);
                    double ab=q.len(),ac=c[i].r,bc=c[j].r;
                    if (dblcmp(ab+ac-bc)<=0)
                    {
                        v.push_back(make_pair(-pi,1));
                        v.push_back(make_pair(pi,-1));
                        continue;
                    }
                    if (dblcmp(ab+bc-ac)<=0)continue;
                    if (dblcmp(ab-ac-bc)>0) continue;
                    double th=atan2(q.y,q.x),fai=acos((ac*ac+ab*ab-bc*bc)/(2.0*ac*ab));
                    double a0=th-fai;
                    if (dblcmp(a0+pi)<0)a0+=2*pi;
                    double a1=th+fai;
                    if (dblcmp(a1-pi)>0)a1-=2*pi;
                    if (dblcmp(a0-a1)>0)
                    {
                        v.push_back(make_pair(a0,1));
                        v.push_back(make_pair(pi,-1));
                        v.push_back(make_pair(-pi,1));
                        v.push_back(make_pair(a1,-1));
                    }
                    else
                    {
                        v.push_back(make_pair(a0,1));
                        v.push_back(make_pair(a1,-1));
                    }
                }
                sort(v.begin(),v.end());
                int cur=0;
                for (j=0;j<v.size();j++)
                {
                    if (cur&&dblcmp(v[j].first-pre[cur]))
                    {
                        ans[cur]+=areaarc(v[j].first-pre[cur],c[i].r);
                        ans[cur]+=0.5*point(c[i].p.x+c[i].r*cos(pre[cur]),c[i].p.y+c[i].r*sin(pre[cur])).det(point(c[i].p.x+c[i].r*cos(v[j].first),c[i].p.y+c[i].r*sin(v[j].first)));
                    }
                    cur+=v[j].second;
                    pre[cur]=v[j].first;
                }
            }
            for (i=1;i<=n;i++)
            {
                ans[i]-=ans[i+1];
            }
        }
    };
    struct halfplane:public line
    {
        double angle;
        halfplane(){}
        //表示向量 a->b逆时针(左侧)的半平面
        halfplane(point _a,point _b)
        {
            a=_a;
            b=_b;
        }
        halfplane(line v)
        {
            a=v.a;
            b=v.b;
        }
        void calcangle()
        {
            angle=atan2(b.y-a.y,b.x-a.x);
        }
        bool operator<(const halfplane &b)const
        {
            return angle<b.angle;
        }
    };
    struct halfplanes
    {
        int n;
        halfplane hp[maxp];
        point p[maxp];
        int que[maxp];
        int st,ed;
        void push(halfplane tmp)
        {
            hp[n++]=tmp;
        }
        void unique()
        {
            int m=1,i;
            for (i=1;i<n;i++)
            {
                if (dblcmp(hp[i].angle-hp[i-1].angle))hp[m++]=hp[i];
                else if (dblcmp(hp[m-1].b.sub(hp[m-1].a).det(hp[i].a.sub(hp[m-1].a))>0))hp[m-1]=hp[i];
            }
            n=m;
        }
        bool halfplaneinsert()
        {
            int i;
            for (i=0;i<n;i++)hp[i].calcangle();
            sort(hp,hp+n);
            unique();
            que[st=0]=0;
            que[ed=1]=1;
            p[1]=hp[0].crosspoint(hp[1]);
            for (i=2;i<n;i++)
            {
                while (st<ed&&dblcmp((hp[i].b.sub(hp[i].a).det(p[ed].sub(hp[i].a))))<0)ed--;
                while (st<ed&&dblcmp((hp[i].b.sub(hp[i].a).det(p[st+1].sub(hp[i].a))))<0)st++;
                que[++ed]=i;
                if (hp[i].parallel(hp[que[ed-1]]))return false;
                p[ed]=hp[i].crosspoint(hp[que[ed-1]]);
            }
            while (st<ed&&dblcmp(hp[que[st]].b.sub(hp[que[st]].a).det(p[ed].sub(hp[que[st]].a)))<0)ed--;
            while (st<ed&&dblcmp(hp[que[ed]].b.sub(hp[que[ed]].a).det(p[st+1].sub(hp[que[ed]].a)))<0)st++;
            if (st+1>=ed)return false;
            return true;
        }
        void getconvex(polygon &con)
        {
            p[st]=hp[que[st]].crosspoint(hp[que[ed]]);
            con.n=ed-st+1;
            int j=st,i=0;
            for (;j<=ed;i++,j++)
            {
                con.p[i]=p[j];
            }
        }
    };
    struct point3
    {
        double x,y,z;
        point3(){}
        point3(double _x,double _y,double _z):
        x(_x),y(_y),z(_z){};
        void input()
        {
            scanf("%lf%lf%lf",&x,&y,&z);
        }
        void output()
        {
            printf("%.2lf %.2lf %.2lf\n",x,y,z);
        }
        bool operator==(point3 a)
        {
            return dblcmp(a.x-x)==0&&dblcmp(a.y-y)==0&&dblcmp(a.z-z)==0;
        }
        bool operator<(point3 a)const
        {
            return dblcmp(a.x-x)==0?dblcmp(y-a.y)==0?dblcmp(z-a.z)<0:y<a.y:x<a.x;
        }
        double len()
        {
            return sqrt(len2());
        }
        double len2()
        {
            return x*x+y*y+z*z;
        }
        double distance(point3 p)
        {
            return sqrt((p.x-x)*(p.x-x)+(p.y-y)*(p.y-y)+(p.z-z)*(p.z-z));
        }
        point3 add(point3 p)
        {
            return point3(x+p.x,y+p.y,z+p.z);
        }
        point3 sub(point3 p)
        {
            return point3(x-p.x,y-p.y,z-p.z);
        }
        point3 mul(double d)
        {
            return point3(x*d,y*d,z*d);
        }
        point3 div(double d)
        {
            return point3(x/d,y/d,z/d);
        }
        double dot(point3 p)
        {
            return x*p.x+y*p.y+z*p.z;
        }
        point3 det(point3 p)
        {
            return point3(y*p.z-p.y*z,p.x*z-x*p.z,x*p.y-p.x*y);
        }
        double rad(point3 a,point3 b)
        {
            point3 p=(*this);
            return acos(a.sub(p).dot(b.sub(p))/(a.distance(p)*b.distance(p)));
        }
        point3 trunc(double r)
        {
            r/=len();
            return point3(x*r,y*r,z*r);
        }
        point3 rotate(point3 o,double r)
        {
        }
    };
    struct line3
    {
        point3 a,b;
        line3(){}
        line3(point3 _a,point3 _b)
        {
            a=_a;
            b=_b;
        }
        bool operator==(line3 v)
        {
            return (a==v.a)&&(b==v.b);
        }
        void input()
        {
            a.input();
            b.input();
        }
        double length()
        {
            return a.distance(b);
        }
        bool pointonseg(point3 p)
        {
            return dblcmp(p.sub(a).det(p.sub(b)).len())==0&&dblcmp(a.sub(p).dot(b.sub(p)))<=0;
        }
        double dispointtoline(point3 p)
        {
            return b.sub(a).det(p.sub(a)).len()/a.distance(b);
        }
        double dispointtoseg(point3 p)
        {
            if (dblcmp(p.sub(b).dot(a.sub(b)))<0||dblcmp(p.sub(a).dot(b.sub(a)))<0)
            {
                return min(p.distance(a),p.distance(b));
            }
            return dispointtoline(p);
        }
        point3 lineprog(point3 p)
        {
            return a.add(b.sub(a).trunc(b.sub(a).dot(p.sub(a))/b.distance(a)));
        }
        point3 rotate(point3 p,double ang)//p绕此向量逆时针arg角度
        {
            if (dblcmp((p.sub(a).det(p.sub(b)).len()))==0)return p;
            point3 f1=b.sub(a).det(p.sub(a));
            point3 f2=b.sub(a).det(f1);
            double len=fabs(a.sub(p).det(b.sub(p)).len()/a.distance(b));
            f1=f1.trunc(len);f2=f2.trunc(len);
            point3 h=p.add(f2);
            point3 pp=h.add(f1);
            return h.add((p.sub(h)).mul(cos(ang*1.0))).add((pp.sub(h)).mul(sin(ang*1.0)));
        }
    };
    struct plane
    {
        point3 a,b,c,o;
        plane(){}
        plane(point3 _a,point3 _b,point3 _c)
        {
            a=_a;
            b=_b;
            c=_c;
            o=pvec();
        }
        plane(double _a,double _b,double _c,double _d)
        {
            //ax+by+cz+d=0
            o=point3(_a,_b,_c);
            if (dblcmp(_a)!=0)
            {
                a=point3((-_d-_c-_b)/_a,1,1);
            }
            else if (dblcmp(_b)!=0)
            {
                a=point3(1,(-_d-_c-_a)/_b,1);
            }
            else if (dblcmp(_c)!=0)
            {
                a=point3(1,1,(-_d-_a-_b)/_c);
            }
        }
        void input()
        {
            a.input();
            b.input();
            c.input();
            o=pvec();
        }
        point3 pvec()
        {
            return b.sub(a).det(c.sub(a));
        }
        bool pointonplane(point3 p)//点是否在平面上
        {
            return dblcmp(p.sub(a).dot(o))==0;
        }
        //0 不在
        //1 在边界上
        //2 在内部
        int pointontriangle(point3 p)//点是否在空间三角形abc上
        {
            if (!pointonplane(p))return 0;
            double s=a.sub(b).det(c.sub(b)).len();
            double s1=p.sub(a).det(p.sub(b)).len();
            double s2=p.sub(a).det(p.sub(c)).len();
            double s3=p.sub(b).det(p.sub(c)).len();
            if (dblcmp(s-s1-s2-s3))return 0;
            if (dblcmp(s1)&&dblcmp(s2)&&dblcmp(s3))return 2;
            return 1;
        }
        //判断两平面关系
        //0 相交
        //1 平行但不重合
        //2 重合
        bool relationplane(plane f)
        {
            if (dblcmp(o.det(f.o).len()))return 0;
            if (pointonplane(f.a))return 2;
            return 1;
        }
        double angleplane(plane f)//两平面夹角
        {
            return acos(o.dot(f.o)/(o.len()*f.o.len()));
        }
        double dispoint(point3 p)//点到平面距离
        {
            return fabs(p.sub(a).dot(o)/o.len());
        }
        point3 pttoplane(point3 p)//点到平面最近点
        {
            line3 u=line3(p,p.add(o));
            crossline(u,p);
            return p;
        }
        int crossline(line3 u,point3 &p)//平面和直线的交点
        {
            double x=o.dot(u.b.sub(a));
            double y=o.dot(u.a.sub(a));
            double d=x-y;
            if (dblcmp(fabs(d))==0)return 0;
            p=u.a.mul(x).sub(u.b.mul(y)).div(d);
            return 1;
        }
        int crossplane(plane f,line3 &u)//平面和平面的交线
        {
            point3 oo=o.det(f.o);
            point3 v=o.det(oo);
            double d=fabs(f.o.dot(v));
            if (dblcmp(d)==0)return 0;
            point3 q=a.add(v.mul(f.o.dot(f.a.sub(a))/d));
            u=line3(q,q.add(oo));
            return 1;
        }
    };
    





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  • 原文地址:https://www.cnblogs.com/cyendra/p/3226302.html
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