poj1979 Red and Black

 1 //Accepted    164 KB    0 ms
 2 #include <cstdio>
 3 #include <cstring>
 4 #include <iostream>
 5 #include <queue>
 6 using namespace std;
 7 queue<int > qx,qy;
 8 int n,m;
 9 int ans;
10 int d[][2]={1,0,-1,0,0,1,0,-1};
11 int vis[20][20];
12 char s[25][25];
13 int rx,ry;
14 void bfs(int i,int j)
15 {
16     memset(vis,0,sizeof(vis));
17     while (!qx.empty()) qx.pop();
18     while (!qy.empty()) qy.pop();
19     qx.push(i);
20     qy.push(j);
21     ans=0;
22     vis[i][j]=1;
23     while (!qx.empty())
24     {
25         int x,y;
26         x=qx.front();
27         qx.pop();
28         y=qy.front();
29         qy.pop();
30         ans++;
31         int nx,ny;
32         for (int i=0;i<4;i++)
33         {
34             nx=x+d[i][0];
35             ny=y+d[i][1];
36             if (nx>=0 && nx<n && ny>=0 && ny<m && s[nx][ny]==‘.‘ && vis[nx][ny]==0)
37             {
38                 qx.push(nx);
39                 qy.push(ny);
40                 vis[nx][ny]=1;
41             }
42         }
43     }
44 }
45 int main()
46 {
47     while (scanf("%d%d",&m,&n),n+m)
48     {
49         for (int i=0;i<n;i++)
50         {
51             scanf("%s",s[i]);
52             for (int j=0;j<m;j++)
53             if (s[i][j]==‘@‘)
54             {
55                 rx=i;
56                 ry=j;
57             }
58         }
59         bfs(rx,ry);
60         printf("%d\n",ans);
61     }
62     return 0;
63 }