1 struct Vector3{    //方向向量 
 2     double x,y,z;
 3 };
 4 double xmulti3(Vector3 v1,Vector3 v2)    //三维向量的叉积 
 5 {
 6     double x1 = v1.x;
 7     double y1 = v1.y;
 8     double z1 = v1.z;
 9     double x2 = v2.x;
10     double y2 = v2.y;
11     double z2 = v2.z;
12     double x = y1*z2 - z1*y2;
13     double y = z1*x2 - x1*z2;
14     double z = x1*y2 - y1*x2;
15     return sqrt(x*x+y*y+z*z);
16 }

 1 #include <iostream>
 2 #include <cmath>
 3 using namespace std;
 4 struct Vector3{    //方向向量 
 5     double x,y,z;
 6 };
 7 double xmulti3(Vector3 v1,Vector3 v2)    //三维向量的叉积 
 8 {
 9     double x1 = v1.x;
10     double y1 = v1.y;
11     double z1 = v1.z;
12     double x2 = v2.x;
13     double y2 = v2.y;
14     double z2 = v2.z;
15     double x = y1*z2 - z1*y2;
16     double y = z1*x2 - x1*z2;
17     double z = x1*y2 - y1*x2;
18     return sqrt(x*x+y*y+z*z);
19 }
20 int main()
21 {
22     double h1,r1,x1,y1,z1;
23     double h2,r2,x2,y2,z2,x3,y3,z3;
24     int T;
25     cin>>T;
26     while(T--){
27         cin>>h1>>r1>>x1>>y1>>z1;
28         cin>>h2>>r2>>x2>>y2>>z2>>x3>>y3>>z3;
29         Vector3 v1,v2;
30         //确定警头心到匪头心的射线 
31         v1.x = x1 - x2;
32         v1.y = y1 - y2;
33         v1.z = z1 + h1 -r1 - ( h2*0.9 + z2 -r2);
34         //确定子弹射线
35         v2.x = x3;
36         v2.y = y3;
37         v2.z = z3; 
38         //求匪的头心到射线的距离 
39         double dis = fabs(xmulti3(v1,v2))/sqrt(x3*x3+y3*y3+z3*z3);
40         //判断能否爆头 
41         if(dis <= r1)
42             cout<<"YES"<<endl;
43         else 
44             cout<<"NO"<<endl;
45     }
46     return 0;
47 }