1 #include<stdio.h>
 2 #include<math.h>
 3 #define MAXN 102
 4 struct pos{
 5     int x,y;
 6 };
 7 struct pos p[MAXN];
 8 int n,d,flag;
 9 int g[MAXN][MAXN],vis[MAXN];
10 double dis(struct pos p1,struct pos p2);
11 void read();
12 void creatg();
13 void dfs(int x);
14 int main(){
15     flag=0;
16     read();
17     creatg();    
18     dfs(0);
19     if(flag==1) printf("Yes\n");
20     else printf("No\n");
21     return 0;
22 }
23 void read(){
24     int i;
25     scanf("%d %d",&n,&d);
26     for(i=1;i<=n;i++) scanf("%d %d",&p[i].x,&p[i].y);
27     for(i=0;i<=n+1;i++) vis[i] = 0;
28 }
29 double dis(struct pos p1,struct pos p2){
30     double t1 = pow((p1.x-p2.x),2) +  pow((p1.y-p2.y),2);
31     return sqrt(t1);
32 }
33 void creatg(){
34     int i,j;
35     struct pos o;
36     o.x = 0;
37     o.y = 0;
38     for(i=0;i<=n+1;i++)
39       for(j=0;j<=n+1;j++)
40          g[i][j] = 0;
41          
42     for(i=1;i<=n;i++){
43         if((dis(o,p[i])-15/2.0)<=d){
44         //if((dis(o,p[i]))<=d){
45             g[0][i] = 1;
46             g[i][0] = 1;
47         }
48         else {
49             g[0][i]=0;
50             g[i][0]=0;    
51         }
52         
53         if((50-abs(p[i].x))<=d || ((50-abs(p[i].y))<=d)) {
54             //可达
55             g[n+1][i] = 1;
56             g[i][n+1] = 1; 
57         }
58         else{
59             g[n+1][i]=0;
60             g[i][n+1]=0;
61         }
62     }
63     for(i=1;i<=n;i++){
64         for(j=1;j<=n;j++){
65             if(i==j){
66                 g[i][j] = 0;
67                 g[j][i] = 0;
68             }
69             else{
70                 if(dis(p[i],p[j])<=d){
71                     g[i][j] = 1;
72                     g[j][i] = 1;
73                 }
74                 else {
75                     g[i][j] = 0;
76                     g[j][i] = 0;    
77                 }
78             }
79         }
80     }
81     
82 
83 }
84 void dfs(int x){
85     vis[x] = 1;
86     //printf("%d\n",x); 
87     if(x==n+1) flag=1;
88     int i;
89     for(i=1;i<=n+1;i++){
90         if(i!=x&&vis[i]==0&&g[x][i]!=0) dfs(i);
91     }
92 }

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