Wireless Network POJ - 2236

Wireless Network

思路：并查集，如果两个点可以相互传达，就是两个集合的合并，当然，前提是要两个点都被维修过。

 1 #include 
 2 #include 
 3 #include 
 4 #include 
 5 #include 
 6 #include 
 7 
 8 using namespace std;
 9 
10 #define ll long long
11 #define pb push_back
12 #define fi first
13 #define se second
14 
15 const int N = 1010;
16 vectorint ,int > > vp;
17 int G[N][N];
18 int fa[N], vis[N];
19 int n, d;
20 
21 inline int dis(int x, int y)
22 {
23     return (vp[x].fi - vp[y].fi) * (vp[x].fi - vp[y].fi) + (vp[x].se - vp[y].se) * (vp[x].se - vp[y].se);
24 } 
25 
26 void build()
27 {   
28     for(int i = 0; i < n; ++i){
29         for(int j = 0; j < n; ++j){
30             G[i][j] = dis(i, j);
31         }
32     }
33 }
34 
35 int Find(int x)
36 {
37     return fa[x] == x ? x : fa[x] = Find(fa[x]);
38 }
39 
40 void Union(int x, int y)
41 {
42     int fax = Find(x);
43     int fay = Find(y);
44 
45     if(fax == fay) return;
46     fa[fax] = fay;
47 }
48 
49 void solve()
50 {
51     scanf("%d%d", &n, &d);
52     d *= d;
53     int xx, yy;
54     for(int i = 0; i < n; ++i){
55         scanf("%d%d", &xx, &yy);
56         vp.pb({xx, yy});
57     }
58 
59     build();
60 
61     for(int i = 0; i < n; ++i) fa[i] = i;
62 
63     char op[2];
64     int x, y;
65     while(~scanf("%s", op)){
66         if(op[0] == 'O'){
67             scanf("%d", &x);
68             vis[--x] = 1;//标记该点被修理过
69             for(int i = 0; i < n; ++i){
70                 if(i != x && G[x][i] <= d && vis[i]){
71                     Union(x, i);
72                 }
73             }
74         }else{
75             scanf("%d%d", &x, &y);
76             int fax = Find(--x);
77             int fay = Find(--y);
78             if(fax == fay) printf("SUCCESS\n");
79             else printf("FAIL\n");
80         }
81     }
82 }
83 
84 int main()
85 {
86 
87     solve();
88 
89     return 0;
90 }