Intersection

 1 #include<cmath>
 2 #include<cstring>
 3 #include<cstdio>
 4 #include<algorithm>
 5 #define Vec point
 6 using namespace std;
 7 const double eps=1e-9;
 8 int n;
 9 struct point{
10     double x,y;
11     void read(){scanf("%lf%lf",&x,&y);}
12 }seg1a,seg1b,seg2a,seg2b,seg3a,seg3b,seg4a,seg4b,seg0a,seg0b,ans;
13 int fabso(double x){return x<-eps?-1:x>eps;}
14 Vec operator + (point u,Vec v){
15     Vec ret; ret.x=u.x+v.x,ret.y=u.y+v.y;
16     return ret;
17 }
18 Vec operator - (point u,point v){
19     Vec ret; ret.x=u.x-v.x,ret.y=u.y-v.y;
20     return ret;
21 }
22 Vec operator * (Vec u,double v){
23     Vec ret; ret.x=u.x*v,ret.y=u.y*v;
24     return ret;
25 }
26 Vec operator / (Vec u,double v){
27     Vec ret; ret.x=u.x/v,ret.y=u.y/v;
28     return ret;
29 }
30 double cross(Vec u,Vec v){return u.x*v.y-u.y*v.x;}
31 bool dotonseg(point P,point U,point V){
32     if ((P.x-U.x)*(P.x-V.x)>0) return 0;
33     if ((P.y-U.y)*(P.y-V.y)>0) return 0;
34     return cross(P-U,V-U)==0;
35 }
36 bool intersect(point P,point Q,point U,point V){
37     if (fabso(cross(P-U,V-U)*cross(Q-U,V-U))<0&&fabso(cross(U-P,Q-P)*cross(V-P,Q-P))<0) return 1;
38     bool g1=dotonseg(P,U,V);
39     bool g2=dotonseg(Q,U,V);
40     bool g3=dotonseg(U,P,Q);
41     bool g4=dotonseg(V,P,Q);
42     if (g1||g2||g3||g4) return 1;
43     return 0;
44 }
45 bool side(point P,point Q,point U,point V){
46     return cross(P-U,V-U)>0;
47 }
48 int main(){
49     int T;
50     for (scanf("%d",&T); T; T--){
51         seg0a.read(),seg0b.read();
52         double a,b,c,d; scanf("%lf%lf%lf%lf",&a,&b,&c,&d);
53         if (a>c) swap(a,c); if (b<d) swap(b,d);
54         seg1a.x=a,seg1a.y=b,seg1b.x=a,seg1b.y=d;
55         seg2a.x=a,seg2a.y=d,seg2b.x=c,seg2b.y=d;
56         seg3a.x=c,seg3a.y=d,seg3b.x=c,seg3b.y=b;
57         seg4a.x=c,seg4a.y=b,seg4b.x=a,seg4b.y=b;
58         bool f1=intersect(seg0a,seg0b,seg1a,seg1b);
59         bool f2=intersect(seg0a,seg0b,seg2a,seg2b);
60         bool f3=intersect(seg0a,seg0b,seg3a,seg3b);
61         bool f4=intersect(seg0a,seg0b,seg4a,seg4b);
62         if (f1||f2||f3||f4) puts("T");
63         else{
64             f1=side(seg0a,seg0b,seg1a,seg1b);
65             f2=side(seg0a,seg0b,seg2a,seg2b);
66             f3=side(seg0a,seg0b,seg3a,seg3b);
67             f4=side(seg0a,seg0b,seg4a,seg4b);
68             if (f1==f2&&f2==f3&&f3==f4) puts("T"); else puts("F");
69         } 
70     }
71     return 0;
72 }