广搜——连通块

 1 #include<cstdio>
 2 #include<iostream>
 3 #include<cstring>
 4 #include<string>
 5 
 6 using namespace std;
 7 const int maxn = 2005;
 8 int j[maxn][maxn],room[maxn][maxn];
 9 long long int total = 0,m,n;
10 struct pos{
11     int x;
12     int y;
13 };
14 pos q[4000000];
15 pos dir[4];
16 
17 
18 int bfs(int y,int x){
19     int h = 0,t = 0;
20     q[0].y = y;
21     q[0].x = x;
22     int tx,ty;
23     while(h <= t){
24         
25         int r3 = 0;
26         for(r3 = 0;r3 <  4;r3++){
27             x = q[h].x;
28             y = q[h].y;
29             tx = dir[r3].x;
30             ty = dir[r3].y;
31             if(y + ty >= 0 && y + ty < n && x + tx >= 0 && x + tx < m && room[y + ty][x + tx] && j[y + ty][x + tx]){
32                 t++;
33                 q[t].y = y + ty;
34                 q[t].x = x + tx;
35                 j[y + ty][x + tx] = 0;
36                 total--;
37             }
38         }
39         h++ ;
40     }
41 }
42 
43 int main(){
44     cin>>n>>m;
45     dir[0].x = -1;dir[0].y = 0;
46     dir[1].x = +1;dir[1].y = 0;
47     dir[2].x = 0;dir[2].y = -1;
48     dir[3].x = 0;dir[3].y = +1;
49     char cmd;
50     int r1 = 0,r2 = 0,temp = -1;
51     for(r1 = 0;r1 < n;r1++){
52         for(r2 = 0;r2 < m;r2++){
53             cin>>cmd;
54             if(cmd == ‘.‘) {
55             j[r1][r2] = 1;
56             room[r1][r2] = 1;
57             total++;
58         }else if(cmd == ‘#‘){
59             j[r1][r2] = 1;
60             room[r1][r2] = 0;
61         } 
62         }
63     }
64     r1 = r2 =0;
65     for(r1 = 0;r1 < n;r1++){
66         for(r2 = 0;r2 < m;r2++){
67             if(room[r1][r2] && j[r1][r2]){
68                 j[r1][r2] = 0;
69                 bfs(r1,r2);
70             }
71 
72         }
73     }
74     cout<<total;
75     return 0;
76 }