Radar Installation

 1 #include<stdio.h>
 2 #include<string.h>
 3 #include<algorithm>
 4 #include<math.h>
 5 using namespace std;
 6 struct node{
 7     double x;
 8     double y;
 9     double l;
10     double r;
11 }island[1005];
12 
13 bool cmp(node a,node b)
14 {
15     if(a.r!=b.r)
16         return a.r<b.r;
17     else
18         return a.l>b.l;
19 }
20 
21 int main()
22 {
23     int n,i,j,k,t=0,flg,num;
24     double d,local;
25     while(scanf("%d %lf",&n,&d)!=EOF)
26     {
27         flg=1;t++;num=1;
28         if(n==0 && d==0)
29         {
30             break;
31         }
32         for(i=1;i<=n;i++)
33         {
34             scanf("%lf %lf",&island[i].x,&island[i].y);
35             if(island[i].y>d)
36                 flg=0;
37         }
38         if(flg==0)
39         {
40             printf("Case %d: -1\n",t);
41             continue;
42         }
43         for(i=1;i<=n;i++)
44         {
45             island[i].l=island[i].x-sqrt(d*d-island[i].y*island[i].y);
46             island[i].r=island[i].x+sqrt(d*d-island[i].y*island[i].y);
47         }
48         sort(island+1,island+n+1,cmp);
49         local=island[1].r;
50         for(i=2;i<=n;i++)
51         {
52             if(island[i].l<=local)
53                 continue;
54             else
55             {
56                 num++;
57                 local=island[i].r;
58             }
59         }
60         printf("Case %d: %d\n",t,num);
61     }
62     return 0;
63 }