【旋转卡壳】poj3608 Bridge Across Islands

#include<cstdio>
#include<cmath>
#include<algorithm>
using namespace std;
#define EPS 0.0000000001
struct Point
{
	double x,y;
	Point(){}
	Point(const double &X,const double &Y)
	  {
	  	x=X;
	  	y=Y;
	  }
	double Length()
	  {
	  	return sqrt(x*x+y*y);
	  }
}p[2][10010],bao[2][10010],ave;
typedef Point Vector;
Vector operator - (const Point &a,const Point &b)
{
	return Vector(a.x-b.x,a.y-b.y);
}
bool cmp (const Point &a,const Point &b)
{
	return atan2((a-ave).y,(a-ave).x)<atan2((b-ave).y,(b-ave).x);
}
double Cross(const Vector &a,const Vector &b)
{
	return a.x*b.y-a.y*b.x;
}
double Dot(const Vector &a,const Vector &b)
{
	return a.x*b.x+a.y*b.y;
}
double calc(Point P,Point A,Point B)
{
	Vector v1=B-A,v2=P-A,v3=P-B;
	if(Dot(v1,v2)<EPS) return v2.Length();
	else if(Dot(v1,v3)>(-EPS)) return v3.Length();
	else return fabs(Cross(v1,v2))/v1.Length();
}
int n,m;
int main()
{
	//freopen("y.in","r",stdin);
	while(1)
	  {
	  	scanf("%d%d",&n,&m);
	  	if(n==0 && m==0)
	  	  break;
	  	for(int i=0;i<n;++i)
	  	  {
	  	  	scanf("%lf%lf",&p[0][i].x,&p[0][i].y);
	  	  	ave.x+=p[0][i].x;
	  	  	ave.y+=p[0][i].y;
	  	  }
	  	ave.x/=(double)n;
	  	ave.y/=(double)n;
	  	for(int i=0;i<m;++i)
	  	  scanf("%lf%lf",&p[1][i].x,&p[1][i].y);
		sort(p[0],p[0]+n,cmp);
		ave.x=ave.y=0;
		for(int i=0;i<m;++i)
		  {
		  	ave.x+=p[1][i].x;
	  	  	ave.y+=p[1][i].y;
		  }
	  	ave.x/=(double)m;
	  	ave.y/=(double)m;
		sort(p[1],p[1]+m,cmp);
	  	int nowP=0,nowQ=0;
	  	for(int i=1;i<n;++i)
	  	  if(p[0][i].y-p[0][nowP].y<(-EPS))
	  	    nowP=i;
	  	for(int i=1;i<m;++i)
	  	  if(p[1][i].y-p[1][nowQ].y>EPS)
	  	    nowQ=i;
	  	double ans=1000000000000000007.0;
	  	for(int i=0;i<n;++i)
		  {
			while(Cross(p[1][(nowQ+1)%m]-p[1][nowQ],p[0][nowP]-p[0][(nowP+1)%n])>EPS)
			  nowQ=(nowQ+1)%m;
			ans=min(ans,
			min(calc(p[0][nowP],p[1][nowQ],p[1][(nowQ+1)%m]),
			min(calc(p[0][(nowP+1)%n],p[1][nowQ],p[1][(nowQ+1)%m]),
			min(calc(p[1][nowQ],p[0][nowP],p[0][(nowP+1)%n]),
			calc(p[1][(nowQ+1)%m],p[0][nowP],p[0][(nowP+1)%n])))));
			nowP=(nowP+1)%n;
		  }
		printf("%.5lf\n",ans);
	  }
	return 0;
}