http://acm.hdu.edu.cn/showproblem.php?pid=4617
三维几何简单题 多谢高尚博学长留下的模板
代码:
#include <iostream> #include <cstdio> #include <algorithm> #include <cstring> #include <cmath> using namespace std; typedef long long ll; typedef pair<double,double>ppd; const double PI = acos(-1.); const int MAXL = (1 << 18)+100; const double eps = (1e-9); const int N=50; struct point3{double x,y,z;}; struct line3{point3 a,b;}; double r[N]; line3 L[N]; int dcmp(double x) { if(fabs(x)<eps) return 0; return x<0?-1:1; } point3 xmult(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; } double dmult(point3 u,point3 v) { return u.x*v.x+u.y*v.y+u.z*v.z; } 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; } double vlen(point3 p) { return sqrt(p.x*p.x+p.y*p.y+p.z*p.z); } double dist(point3 u,point3 v) { return (double)(sqrt((u.x-v.x)*(u.x-v.x)+(u.y-v.y)*(u.y-v.y)+(u.z-v.z)*(u.z-v.z))); } double ptoline(point3 p,line3 l) { l.b.x=l.a.x+l.b.x; l.b.y=l.a.y+l.b.y; l.b.z=l.a.z+l.b.z; return vlen(xmult(subt(p,l.a),subt(l.b,l.a)))/dist(l.a,l.b); } double linetoline(line3 u,line3 v) { point3 n=xmult(u.b,v.b); if(dcmp(vlen(n))==0) return ptoline(u.a,v); return fabs(dmult(subt(v.a,u.a),n))/vlen(n); } point3 pvec(point3 s1,point3 s2,point3 s3) { return xmult(subt(s1,s2),subt(s2,s3)); } int main() { //freopen("data.in","r",stdin); int T; scanf("%d",&T); while(T--) { int n; scanf("%d",&n); for(int i=0;i<n;++i) { point3 p[3]; for(int j=0;j<3;++j) scanf("%lf %lf %lf",&p[j].x,&p[j].y,&p[j].z); L[i].a=p[0]; L[i].b=pvec(p[0],p[1],p[2]); r[i]=dist(p[0],p[1]); } double k=1e9; for(int i=0;i<n;++i) for(int j=i+1;j<n;++j) { //cout<<linetoline(L[i],L[j])<<endl; k=min(k,linetoline(L[i],L[j])-r[i]-r[j]); } if(dcmp(k)<=0) printf("Lucky "); else printf("%.2lf ",k); } return 0; }