hdu 4741 Save Labman No.004 (异面直线的距离)

转载学习：

#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <algorithm>
#include <cmath>

using namespace std;

const double EPS = 1e-;
const int MAXN = ;

struct Point3  //空间点
{
    double x, y, z;
    Point3( double x=, double y=, double z= ): x(x), y(y), z(z) { }
    Point3( const Point3& a )
    {
        x = a.x;
        y = a.y;
        z = a.z;
        return;
    }
    void showP()
    {
        printf("%f %f %f \n", x, y, z);
    }
    Point3 operator+( Point3& rhs )
    {
        return Point3( x+rhs.x, y+rhs.y, z+rhs.z );
    }
};

struct Line3   //空间直线
{
    Point3 a, b;
};

struct plane3   //空间平面
{
    Point3 a, b, c;
    plane3() {}
    plane3( Point3 a, Point3 b, Point3 c ):
        a(a), b(b), c(c) { }
    void showPlane()
    {
        a.showP();
        b.showP();
        c.showP();
        return;
    }
};

double dcmp( double a )
{
    if ( fabs( a ) < EPS ) return ;
    return a <  ? - : ;
}

//三维叉积
Point3 Cross3( Point3 u, Point3 v )
{
    Point3 ret;
    ret.x = u.y * v.z - v.y * u.z;
    ret.y = u.z * v.x - u.x * v.z;
    ret.z = u.x * v.y - u.y * v.x;
    return ret;
}

//三维点积
double Dot3( Point3 u, Point3 v )
{
    return u.x * v.x + u.y * v.y + u.z * v.z;
}

//矢量差
Point3 Subt( Point3 u, Point3 v )
{
    Point3 ret;
    ret.x = u.x - v.x;
    ret.y = u.y - v.y;
    ret.z = u.z - v.z;
    return ret;
}

//两点距离
double TwoPointDistance( Point3 p1, Point3 p2 )
{
    return sqrt( (p1.x - p2.x)*(p1.x - p2.x) + (p1.y - p2.y)*(p1.y - p2.y) + (p1.z - p2.z)*(p1.z - p2.z) );
}

//向量的模
double VectorLenth( Point3 p )
{
    return sqrt( p.x*p.x + p.y*p.y + p.z*p.z );
}

//空间直线距离
double LineToLine( Line3 u, Line3 v, Point3& tmp )
{
    tmp = Cross3( Subt( u.a, u.b ), Subt( v.a, v.b ) );
    return fabs( Dot3( Subt(u.a, v.a), tmp ) ) / VectorLenth(tmp);
}

//取平面法向量
Point3 pvec( plane3 s )
{
    return Cross3( Subt( s.a, s.b ), Subt( s.b, s.c ) );
}

//空间平面与直线的交点
Point3 Intersection( Line3 l, plane3 s )
{
    Point3 ret = pvec(s);
    double t = ( ret.x*(s.a.x-l.a.x)+ret.y*(s.a.y-l.a.y)+ret.z*(s.a.z-l.a.z) )/( ret.x*(l.b.x-l.a.x)+ret.y*(l.b.y-l.a.y)+ret.z*(l.b.z-l.a.z) );
    ret.x = l.a.x + ( l.b.x - l.a.x ) * t;
    ret.y = l.a.y + ( l.b.y - l.a.y ) * t;
    ret.z = l.a.z + ( l.b.z - l.a.z ) * t;
    return ret;
}

/************以上模板*************/

void solved( Line3 A, Line3 B )
{
    Point3 normal;
    double dis = LineToLine( A, B, normal );
    printf( "%.6f\n", dis );
    plane3 pla;
    pla = plane3( A.a, A.b, A.a + normal );
    Point3 u = Intersection( B, pla );
    pla = plane3( B.a, B.b, B.a + normal );
    Point3 v = Intersection( A, pla );
    printf("%.6f %.6f %.6f %.6f %.6f %.6f\n", v.x, v.y, v.z, u.x, u.y, u.z );
    return;
}

int main()
{
    int T;
    scanf( "%d", &T );
    while ( T-- )
    {
        Line3 A, B;
        scanf("%lf%lf%lf", &A.a.x, &A.a.y, &A.a.z );
        scanf("%lf%lf%lf", &A.b.x, &A.b.y, &A.b.z );
        scanf("%lf%lf%lf", &B.a.x, &B.a.y, &B.a.z );
        scanf("%lf%lf%lf", &B.b.x, &B.b.y, &B.b.z );
        solved( A, B );
    }
    return ;
}

不知精度误差的WA

#include<stdio.h>
#include<math.h>
#define eps 1e-12
double myfabs(double x)
{
    if(x<)x=-x;
    return x;
}
int main()
{
    int _case;
    /*double xa,xb,xc,xd;
    double ya,yb,yc,yd;
    double za,zb,zc,zd;
*/
    double  Xa,Xb,Xc,Xd,Ya,Yb,Yc,Yd,Za,Zb,Zc,Zd;

    scanf("%d",&_case);
    while(_case--)
    {
        /*scanf("%lf%lf%lf%lf%lf%lf",&xa,&ya,&za,&xb,&yb,&zb);
        scanf("%lf%lf%lf%lf%lf%lf",&xc,&yc,&zc,&xd,&yd,&zd);*/
        scanf("%lf%lf%lf%lf%lf%lf",&Xa,&Ya,&Za,&Xb,&Yb,&Zb);
        scanf("%lf%lf%lf%lf%lf%lf",&Xc,&Yc,&Zc,&Xd,&Yd,&Zd);
        /*long double Xa=(long double)xa;
        long double Xb=(long double)xb;
        long double Xc=(long double)xc;
        long double Xd=(long double)xd;

        long double Ya=(long double)ya;
        long double Yb=(long double)yb;
        long double Yc=(long double)yc;
        long double Yd=(long double)yd;

        long double Za=(long double)za;
        long double Zb=(long double)zb;
        long double Zc=(long double)zc;
        long double Zd=(long double)zd;*/
         double F11=(Xb-Xa)*(Xb-Xa)+(Yb-Ya)*(Yb-Ya)+(Zb-Za)*(Zb-Za);
         double F12= (Xd-Xc)*(Xd-Xc)+(Yd-Yc)*(Yd-Yc)+(Zd-Zc)*(Zd-Zc);
         double F2=(Xb-Xa)*(Xd-Xc)+(Yb-Ya)*(Yd-Yc)+(Zb-Za)*(Zd-Zc);
         double F31=(Xb-Xa)*(Xc-Xa)+(Yb-Ya)*(Yc-Ya)+(Zb-Za)*(Zc-Za);
         double F32=(Xd-Xc)*(Xc-Xa)+(Yd-Yc)*(Yc-Ya)+(Zd-Zc)*(Zc-Za);
         double y=F11*F12-F2*F2;
        //if(myfabs(y)<eps)y=eps;
         double t1=(F31*F12-F32*F2)/y;
         double t2=(F32*F11-F2*F31)/(-y);

         double Xm=t1*(Xb-Xa)+Xa;//=(Xb-Xa)*[F31*F12-F32*F2]/[F11*F12-F2*F2]+Xa;
         double Ym=t1*(Yb-Ya)+Ya;//=(Yb-Ya)*[F31*F12-F32*F2]/[F11*F12-F2*F2]+Ya;
         double Zm=t1*(Zb-Za)+Za;//=(Zb-Za)*[F31*F12-F32*F2]/[F11*F12-F2*F2]+Za;

         double Xn=t2*(Xd-Xc)+Xc;//=(Xd-Xc)*[F3(c,d)*F1(a,b)-F3(a,b)*F2()]/[F2()*F2()-F1(a,b)*F1(c,d)]+Xc;
         double Yn=t2*(Yd-Yc)+Yc;//=(Yd-Yc)*[F3(c,d)*F1(a,b)-F3(a,b)*F2()]/[F2()*F2()-F1(a,b)*F1(c,d)]+Yc;
         double Zn=t2*(Zd-Zc)+Zc;
        double s=sqrt((Xn-Xm)*(Xn-Xm)+(Yn-Ym)*(Yn-Ym)+(Zn-Zm)*(Zn-Zm));

        /*double xm=(double)Xm;//=t1*(Xb-Xa)+Xa;//=(Xb-Xa)*[F31*F12-F32*F2]/[F11*F12-F2*F2]+Xa;
        double ym=(double)Ym;//=t1*(Yb-Ya)+Ya;//=(Yb-Ya)*[F31*F12-F32*F2]/[F11*F12-F2*F2]+Ya;
        double zm=(double)Zm;//=t1*(Zb-Za)+Za;//=(Zb-Za)*[F31*F12-F32*F2]/[F11*F12-F2*F2]+Za;

        double xn=(double)Xn;//=t2*(Xd-Xc)+Xc;//=(Xd-Xc)*[F3(c,d)*F1(a,b)-F3(a,b)*F2()]/[F2()*F2()-F1(a,b)*F1(c,d)]+Xc;
        double yn=(double)Yn;//=t2*(Yd-Yc)+Yc;//=(Yd-Yc)*[F3(c,d)*F1(a,b)-F3(a,b)*F2()]/[F2()*F2()-F1(a,b)*F1(c,d)]+Yc;
        double zn=(double)Zn;
        //printf("%lf\n",eps);*/
        printf("%.6lf\n%.6lf %.6lf %.6lf %.6lf %.6lf %.6lf\n",s,Xm,Ym,Zm,Xn,Yn,Zn);
        //printf("%.6lf\n%.6lf %.6lf %.6lf %.6lf %.6lf %.6lf\n",s,xm,ym,zm,xn,yn,zn);
    }
    return ;
}