680: Jack Straws

#include<bits/stdc++.h>
using namespace std;
const int N=20;
int f[N],n;
struct node{
	int x,y;
}p[N],q[N];
int check(int i,int j){
	if (max(q[i].x,p[i].x)<min(q[j].x,p[j].x)||
		max(q[i].y,p[i].y)<min(q[j].y,p[j].y)||
		max(q[j].x,p[j].x)<min(q[i].x,p[i].x)||
		max(q[j].y,p[j].y)<min(q[i].y,p[i].y))	
		return 0;
	
	int u=(p[j].x-p[i].x)*(q[i].y-p[i].y)-(q[i].x-p[i].x)*(p[j].y-p[i].y);
	int v=(q[j].x-p[i].x)*(q[i].y-p[i].y)-(q[i].x-p[i].x)*(q[j].y-p[i].y);
	int w=(q[i].x-p[j].x)*(q[j].y-p[j].y)-(q[j].x-p[j].x)*(q[i].y-p[j].y);
	int z=(p[i].x-p[j].x)*(q[j].y-p[j].y)-(q[j].x-p[j].x)*(p[i].y-p[j].y);
	return (u*v<=0&&w*z<=0);
}
int get(int x){
	return x==f[x]?x:f[x]=get(f[x]);
}
void union_set(){
	for(int i=1;i<=n;i++)
	{
		for(int j=i+1;j<=n;j++)	if(check(i,j))	f[get(i)]=get(j);
	}
}
int main(){
	while(cin>>n){
		for(int i=1;i<=n;i++)	f[i]=i;
		for(int i=1;i<=n;i++)	cin>>p[i].x>>p[i].y>>q[i].x>>q[i].y;
		union_set();
		int a,b;
		while(cin>>a>>b,a||b){
			if(get(a)==get(b))	cout<<"CONNECTED"<<endl;
			else	cout<<"NOT CONNECTED"<<endl;
		}
	}
	return 0;
}