poj 3862 Asteroids

poj 3862 Asteroids

#include<stdio.h>#include<algorithm>#include<string.h>#include<math.h>#include<stdlib.h>using namespace std;const int MAXN=550;const double eps=1e-8;struct Point{    double x,y,z;    Point(){}    Point(double xx,double yy,double zz):x(xx),y(yy),z(zz){}    Point operator -(const Point p1)    {        return Point(x-p1.x,y-p1.y,z-p1.z);    }    Point operator +(const Point p1)    {        return Point(x+p1.x,y+p1.y,z+p1.z);    }    Point operator *(const Point p)    {        return Point(y*p.z-z*p.y,z*p.x-x*p.z,x*p.y-y*p.x);    }    Point operator *(double d)    {        return Point(x*d,y*d,z*d);    }    Point operator / (double d)    {        return Point(x/d,y/d,z/d);    }    double  operator ^(Point p)    {        return (x*p.x+y*p.y+z*p.z);    }};struct CH3D{    struct face    {        int a,b,c;        bool ok;    };    int n;    Point P[MAXN];    int num;    face F[8*MAXN];    int g[MAXN][MAXN];    double vlen(Point a)    {        return sqrt(a.x*a.x+a.y*a.y+a.z*a.z);    }    //叉乘    Point cross(const Point &a,const Point &b,const Point &c)    {        return Point((b.y-a.y)*(c.z-a.z)-(b.z-a.z)*(c.y-a.y),          (b.z-a.z)*(c.x-a.x)-(b.x-a.x)*(c.z-a.z),          (b.x-a.x)*(c.y-a.y)-(b.y-a.y)*(c.x-a.x)          );    }    //三角形面积*2    double area(Point a,Point b,Point c)    {        return vlen((b-a)*(c-a));    }    //四面体有向体积*6    double volume(Point a,Point b,Point c,Point d)    {        return (b-a)*(c-a)^(d-a);    }    //正：点在面同向    double dblcmp(Point &p,face &f)    {        Point m=P[f.b]-P[f.a];        Point n=P[f.c]-P[f.a];        Point t=p-P[f.a];        return (m*n)^t;    }    void deal(int p,int a,int b)    {        int f=g[a][b];//搜索与该边相邻的另一个平面        face add;        if(F[f].ok)        { if(dblcmp(P[p],F[f])>eps)   dfs(p,f); else {     add.a=b;     add.b=a;     add.c=p;//这里注意顺序，要成右手系     add.ok=true;     g[p][b]=g[a][p]=g[b][a]=num;     F[num++]=add; }        }    }    void dfs(int p,int now)    {         F[now].ok=0;         deal(p,F[now].b,F[now].a);         deal(p,F[now].c,F[now].b);         deal(p,F[now].a,F[now].c);    }    bool same(int s,int t)    {        Point &a=P[F[s].a];        Point &b=P[F[s].b];        Point &c=P[F[s].c];        return fabs(volume(a,b,c,P[F[t].a]))<eps &&    fabs(volume(a,b,c,P[F[t].b]))<eps &&    fabs(volume(a,b,c,P[F[t].c]))<eps;    }    void create()    {        int i,j,tmp;        face add;        num=0;        if(n<4)return;        bool flag=true;        for(i=1;i<n;i++)        { if(vlen(P[0]-P[i])>eps) {     swap(P[1],P[i]);     flag=false;     break; }        }        if(flag)return;        flag=true;        for(i=2;i<n;i++)        { if(vlen((P[0]-P[1])*(P[1]-P[i]))>eps) {     swap(P[2],P[i]);     flag=false;     break; }        }        if(flag)return;        flag=true;        for(int i=3;i<n;i++)        { if(fabs((P[0]-P[1])*(P[1]-P[2])^(P[0]-P[i]))>eps) {     swap(P[3],P[i]);     flag=false;     break; }        }        if(flag)return;        for(i=0;i<4;i++)        { add.a=(i+1)%4; add.b=(i+2)%4; add.c=(i+3)%4; add.ok=true; if(dblcmp(P[i],add)>0)swap(add.b,add.c); g[add.a][add.b]=g[add.b][add.c]=g[add.c][add.a]=num; F[num++]=add;        }        for(i=4;i<n;i++)        { for(j=0;j<num;j++) {     if(F[j].ok&&dblcmp(P[i],F[j])>eps)     {         dfs(i,j);         break;     } }        }        tmp=num;        for(i=num=0;i<tmp;i++)          if(F[i].ok) F[num++]=F[i];    }    double area()    {        double res=0;        if(n==3)        { Point p=cross(P[0],P[1],P[2]); res=vlen(p)/2.0; return res;        }        for(int i=0;i<num;i++)          res+=area(P[F[i].a],P[F[i].b],P[F[i].c]);        return res/2.0;    }    double volume()    {        double res=0;        Point tmp(0,0,0);        for(int i=0;i<num;i++)res+=volume(tmp,P[F[i].a],P[F[i].b],P[F[i].c]);        return fabs(res/6.0);    }    int ***()    {        return num;    }    int polygon()    {        int i,j,res,flag;        for(i=res=0;i<num;i++)        { flag=1; for(j=0;j<i;j++)   if(same(i,j))   {       flag=0;       break;   } res+=flag;        }        return res;    }    Point barycenter()    {        Point ans(0,0,0),o(0,0,0);        double all=0;        for(int i=0;i<num;i++)        { double vol=volume(o,P[F[i].a],P[F[i].b],P[F[i].c]); ans=ans+(o+P[F[i].a]+P[F[i].b]+P[F[i].c])/4.0*vol; all+=vol;        }        ans=ans/all;        return ans;    }    double ptoface(Point p,int i)    {        return fabs(volume(P[F[i].a],P[F[i].b],P[F[i].c],p)/vlen((P[F[i].b]-P[F[i].a])*(P[F[i].c]-P[F[i].a])));    }};CH3D hull;int main(){    while(scanf("%d",&hull.n)==1)    {        for(int i=0;i<hull.n;i++)        { scanf("%lf%lf%lf",&hull.P[i].x,&hull.P[i].y,&hull.P[i].z);        }        hull.create();        Point p=hull.barycenter();        double ans1=1e20;        for(int i=0;i<hull.num;i++)        { ans1=min(ans1,hull.ptoface(p,i));        }        scanf("%d",&hull.n);        for(int i=0;i<hull.n;i++)        { scanf("%lf%lf%lf",&hull.P[i].x,&hull.P[i].y,&hull.P[i].z);        }        hull.create();        p=hull.barycenter();        double ans2=1e20;        for(int i=0;i<hull.num;i++)        { ans2=min(ans2,hull.ptoface(p,i));        }        printf("%.5fn",ans1+ans2);    }    return 0;}