Jack Straws 线段相交加并查集

/*开始的时候并查集写错了。就是有传递闭包的关系。不错的一个题。*/

#include <stdio.h>
#define eps 1e-8
double max(double a,double b)
{
    if(b-a<-eps) return a;
    else return b;
}
double min(double a,double b)
{
    if(b-a<-eps) return b;
    else return a;
}
struct point
{
    double x,y;
};
struct LINE
{
    point p1,p2;
}line[14];
int f[14];
double multi(point p0,point p1,point p2)
{
    return ((p1.x-p0.x)*(p2.y-p0.y)-(p2.x-p0.x)*(p1.y-p0.y));
}
bool cross(LINE a,LINE b)
{
    if(min(a.p1.x,a.p2.x)-max(b.p1.x,b.p2.x)<eps
            &&min(a.p1.y,a.p2.y)-max(b.p1.y,b.p2.y)<eps
            &&min(b.p1.x,b.p2.x)-max(a.p1.x,a.p2.x)<eps
            &&min(b.p1.y,b.p2.y)-max(a.p1.y,a.p2.y)<eps
            &&multi(a.p1,a.p2,b.p1)*multi(a.p1,a.p2,b.p2)<=eps
            &&multi(b.p1,b.p2,a.p1)*multi(b.p1,b.p2,a.p2)<=eps)
        return true;
    else return false;
}
int find(int x)
{
    if(x!=f[x])
        f[x]=find(f[x]);
    return f[x];
}
void unit(int x,int y)
{
    x=find(x);
    y=find(y);
    if(x==y) return ;
    else f[y]=x;
}
int main()
{
    int n,r,t;
    while(scanf("%d",&n)==1&&n)
    {
        for(int i=1; i<=n; i++)
            f[i]=i;
        for(int i=1; i<=n; i++)
            scanf("%lf%lf%lf%lf",&line[i].p1.x,&line[i].p1.y,&line[i].p2.x,&line[i].p2.y);
        for(int i=1; i<=n; i++)
            for(int j=i+1; j<=n; j++)
            {
                if(cross(line[i],line[j]))
                    unit(i,j);
            }
        while(scanf("%d%d",&r,&t)==2)
        {
            if(r==0&&t==0) break;
            if(find(r)==find(t))
                printf("CONNECTED\n");
            else printf("NOT CONNECTED\n");
        }
    }
    return 0;
}

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