1 /**
2 判断直线位置关系
3 **/
4 #include <iostream>
5 #include <cmath>
6 #include <cstdio>
7 using namespace std;
8 struct point {
9 double x,y;
10 point(double x=0,double y=0):x(x),y(y){}
11 };
12
13 typedef point Vector;
14
15 Vector operator - (point A,point B){
16 return Vector(A.x-B.x,A.y-B.y);
17 }
18
19 struct line {
20 point a,b;
21 };
22 double length(Vector v){
23 return sqrt(v.x*v.x+v.y*v.y);
24 }
25
26 double cross(Vector A,Vector B){
27 return A.x*B.y-A.y*B.x;
28 }
29
30 double distoline(point P,point A,point B){
31 Vector v1 =B-A,v2 = P-A;
32 return fabs(cross(v1,v2))/length(v1);
33 }
34
35 int main()
36 {
37 int n;
38 cin>>n;
39 line l1,l2;
40 cout<<"INTERSECTING LINES OUTPUT"<<endl;
41 while(n--){
42 cin>>l1.a.x>>l1.a.y>>l1.b.x>>l1.b.y;
43 cin>>l2.a.x>>l2.a.y>>l2.b.x>>l2.b.y;
44 Vector tmp1,tmp2;
45 tmp1.x = l1.b.x-l1.a.x;
46 tmp1.y = l1.b.y-l1.a.y;
47 tmp2.x = l2.b.x-l2.a.x;
48 tmp2.y = l2.b.y-l2.a.y;
49 //cout<<tmp1.x<<" "<<tmp1.y<<endl;
50 //cout<<tmp2.x<<" "<<tmp2.y<<endl;
51 //cout<<cross(tmp1,tmp2)<<endl;
52 if(cross(tmp1,tmp2)==0){
53 if(distoline(l1.a,l2.a,l2.b)==0){
54 cout<<"LINE"<<endl;
55 }else
56 cout<<"NONE"<<endl;
57 }else{
58 double x,y;
59 if(l1.a.x==l1.b.x&&l2.a.x!=l2.b.x){
60 x = l1.a.x;
61 double k = (l2.b.y-l2.a.y)/(l2.b.x-l2.a.x);
62 double b = l2.a.y-k*l2.a.x;;
63 y = k*x+b;
64 }else if(l1.a.x!=l1.b.x&&l2.a.x==l2.b.x){
65 x = l2.a.x;
66 double k = (l1.b.y-l1.a.y)/(l1.b.x-l1.a.x);
67 double b = l1.a.y-k*l1.a.x;
68 y = k*x+b;
69 }else{
70 double k1= (l1.b.y-l1.a.y)/(l1.b.x-l1.a.x);
71 double b1=l1.a.y-k1*l1.a.x;
72 double k2 = (l2.b.y-l2.a.y)/(l2.b.x-l2.a.x);
73 double b2=l2.a.y-k2*l2.a.x;
74 x =(b2-b1)/(k1-k2);
75 y = k1*x+b1;
76 }
77
78 printf("POINT %.2lf %.2lf\n",x,y);
79 }
80 }
81 cout<<"END OF OUTPUT"<<endl;
82 return 0;
83 }
poj 1269 计算几何
时间： 2024-10-14 16:46:15