fzuoj1111Radar Installation （贪心）

 1 #include <iostream>
 2 #include <cmath>
 3 #include <algorithm>
 4 #include <cstdio>
 5 using namespace std;
 6 struct node
 7 {
 8     double left,right;
 9 }island[1001];
10 bool cmp(node a,node b)
11 {
12     return a.left < b.left;
13 }
14 int main()
15 {
16     double x,y,d,temp;
17     int i,cnt,n,k=0;
18     bool flag;
19     while(scanf("%d%lf",&n,&d)&&!(n==0&&d==0))
20     {
21         k++;
22         flag=false;
23         for(i=0; i<n; i++)
24         {
25             scanf("%lf%lf",&x,&y);
26             if(y > d||d<0)
27             {
28                 flag = true;
29             }
30             island[i].right = x+sqrt(d*d-y*y);///岛屿右端点初始化
31             island[i].left = x-sqrt(d*d-y*y);///岛屿左端点初始化
32         }
33         if(flag)
34         {
35             printf("Case %d: -1\n",k);
36             continue;
37         }
38         sort(island,island+n,cmp);
39         temp=island[0].right;
40         cnt=1;
41         for(i=1; i<n; i++)
42         {
43             if(island[i].right <= temp)
44             {
45                 temp = island[i].right;///岛屿右端点的替换
46             }
47             else if(island[i].left > temp)
48             {
49                 cnt++;
50                 temp = island[i].right;
51             }
52         }
53         printf("Case %d: %d\n",k,cnt);
54     }
55     return 0;
56 }