hdu 1558 判断线段相交 + 并查集

#include<cstdio>
#include<iostream>
using namespace std;
int father[10008];
int find(int x)
{
if(x == father[x])return x;
return father[x] = find(father[x]);
}
int merge(int a,int b)
{
int G = find(a);
int H = find(b);
if(G<H)
father[G] = H;
else
father[H] = G;
}
double fun(double x1,double y1,double x2,double y2)
{
return x1 * y2 - x2 * y1;
}
bool judge(double x1,double y1,double x2,double y2,double a,double a1,double b,double b1) // 判断线段相交
{
double s= x2 - x1,s1 = y2 - y1;
double d1 = fun(s, s1, a-x1, a1-y1);
double d2 = fun(s, s1, b-x1, b1-y1);
s = b - a;
s1 = b1 - a1;
double d3 = fun(x1-a,y1-a1,s,s1);
double d4 = fun(x2-a,y2-a1,s,s1);
// cout<<d1 * d2<<" " << d3 * d4 <<endl;
if(d1 * d2 <= 0 && d3 * d4 <= 0)return true;
return false;
}
struct Node
{
double x1,x2,y1,y2;
}a[100008];
int main()
{
int n,m;
int icase;
char s[10];
double x1,x2,y1,y2;
scanf("%d",&icase);
while(icase --)
{
int k = 1;
scanf("%d",&n);
for(int i=1;i<=n;i++)
father[i] = i;
for(int i=1;i<=n;i++)
{
cin>>s;
if(s[0] == 'P'){
cin>>a[k].x1>>a[k].y1>>a[k].x2>>a[k].y2;
for(int j=1;j<k;j++)
if(judge(a[k].x1,a[k].y1,a[k].x2,a[k].y2,a[j].x1,a[j].y1,a[j].x2,a[j].y2)){
merge(k,j);
}
k++;
}
else
{
int sum = 0;
cin>>m;
int x = find(m);
for(int i=1;i<=n;i++)
{
if(x == find(i))
{
sum++;
}
}
cout<<sum<<endl;
}
}
if(icase>0)puts("");
}
}