hdu 1558 Segment set

 1 #include <cstdio>
 2 #include <cstring>
 3 #include <algorithm>
 4 #define maxn 20000
 5 using namespace std;
 6 
 7 int num[maxn],f[maxn];
 8 
 9 struct point
10 {
11     double x,y;
12 };
13 struct line
14 {
15     point p1,p2;
16 }p[maxn];
17 
18 
19 void inti()
20 {
21     for(int i=0; i<=maxn; i++)
22     {
23         f[i]=i;
24         num[i]=1;
25     }
26 }
27 double det(point a,point b,point c)
28 {
29     return (c.x-a.x)*(b.y-a.y)-(c.y-a.y)*(b.x-a.x);
30 }
31 
32 int find1(int x)
33 {
34     if(x==f[x]) return x;
35     return f[x]=find1(f[x]);
36 }
37 
38 void merge1(int a,int b)
39 {
40     int fa=find1(a);
41     int fb=find1(b);
42     if(fa!=fb)
43     {
44         f[fa]=fb;
45         num[fb]+=num[fa];
46     }
47 }
48 
49 bool Isintsert(line u,line v)
50 {
51     return (det(v.p1,u.p2,u.p1)*det(u.p2,v.p2,u.p1)>=0)&&(det(u.p1,v.p2,v.p1)*det(v.p2,u.p2,v.p1)>=0)&&
52     (max(u.p1.x,u.p2.x)>=min(v.p1.x,v.p2.x))&&
53     (max(v.p1.x,v.p2.x)>=min(u.p1.x,u.p2.x))&&
54     (max(u.p1.y,u.p2.y)>=min(v.p1.y,v.p2.y))&&
55     (max(v.p1.y,v.p2.y))>=min(u.p1.y,u.p2.y);
56 }
57 
58 int main()
59 {
60     int t,n,k1;
61     char ch;
62     scanf("%d",&t);
63     while(t--)
64     {
65         inti();
66         scanf("%d",&n);
67         getchar();
68         int t1=1;
69         for(int i=0; i<n; i++)
70         {
71             scanf("%c",&ch);
72             if(ch==‘P‘)
73             {
74                 scanf("%lf%lf%lf%lf",&p[t1].p1.x,&p[t1].p1.y,&p[t1].p2.x,&p[t1].p2.y);
75                 t1++;
76                 for(int j=1; j<t1-1; j++)
77                 {
78                     int f2=find1(t1-1); int f3=find1(j);
79                     if(f2!=f3&&Isintsert(p[j],p[t1-1]))
80                     {
81                         merge1(j,t1-1);
82                     }
83                 }
84             }
85             else if(ch==‘Q‘)
86             {
87                 scanf("%d",&k1);
88                 int k2=find1(k1);
89                 printf("%d\n",num[k2]);
90             }
91             getchar();
92             
93         }
94         if(t!=0) printf("\n");
95     }
96     return 0;
97 }