hdu 2436

判断一个长方体和一个球是否相交

 

找到一个离求最近的点，然后算这个点到这个球圆心的距离，就能判断出是否相交

 

代码：

 1 #include <cstdio>
 2 #include <cmath>
 3 #include <iostream>
 4 
 5 using namespace std;
 6 
 7 typedef struct point
 8 {
 9     double x,y,z;
10 }point;
11 
12 point a[10];
13 
14 double judge(double x,double y,double z,point q)
15 {
16     double sum = (x-q.x)*(x-q.x) + (y-q.y)*(y-q.y) +(z-q.z)*(z-q.z);
17     sum = sqrt(sum);
18     return sum;
19 }
20 
21 int main()
22 {
23     int T;
24     scanf("%d",&T);
25     while(T--)
26     {
27         int i = 0;
28         for(i = 0; i < 8; i++)
29             scanf("%lf%lf%lf",&a[i].x,&a[i].y,&a[i].z);
30         point b;
31         double r1;
32         scanf("%lf%lf%lf%lf",&b.x,&b.y,&b.z,&r1);
33         double flag = 0;
34         double kk;
35         double xmin,xmax,ymin,ymax,zmin,zmax;
36         double x,y,z;
37 
38         xmin = a[0].x;xmax = a[0].x;
39         ymin = a[0].y;ymax = a[0].y;
40         zmin = a[0].z;zmax = a[0].z;
41 
42         for(i = 1; i < 8; i++)
43         {
44             if(a[i].x < xmin) xmin = a[i].x;
45             if(a[i].x > xmax) xmax = a[i].x;
46             if(a[i].y < ymin) ymin = a[i].y;
47             if(a[i].y > ymax) ymax = a[i].y;
48             if(a[i].z < zmin) zmin = a[i].z;
49             if(a[i].z > zmax) zmax = a[i].z;
50 
51         }
52         if(b.x < xmin) x = xmin;
53         else if(b.x > xmax) x= xmax;
54         else x = b.x;
55 
56         if(b.y < ymin) y = ymin;
57         else if(b.y > ymax) y= ymax;
58         else y = b.y;
59 
60         if(b.z < zmin) z = zmin;
61         else if(b.z > zmax) z= zmax;
62         else z = b.z;
63 
64     if( judge(x,y,z,b) > r1)
65         printf("No\n");
66     else
67         printf("Yes\n");
68     }
69     return 0;
70 }

 

posted @ 2013-04-10 08:14  heity  阅读(187)  评论(0)  编辑  收藏  举报