POJ1979 Red and Black

 1 /*by SilverN*/
 2 #include<iostream>
 3 #include<algorithm>
 4 #include<cstring>
 5 #include<cstdio>
 6 #include<cmath>
 7 using namespace std;
 8 const int mxn=50;
 9 char mp[mxn][mxn];
10 int ans;
11 int W,H;
12 void dfs(int x,int y){
13     if(x<1 || x>H || y<1 || y>W)return;
14     if(mp[x][y]==‘#‘)return;
15     ans++;
16     mp[x][y]=‘#‘;
17     dfs(x+1,y);
18     dfs(x,y+1);
19     dfs(x-1,y);
20     dfs(x,y-1);
21     return;
22 }
23 int main(){
24     while(scanf("%d%d",&W,&H) && W && H){
25         memset(mp,‘ ‘,sizeof(mp));
26         ans=0;
27         int i,j;
28         for(i=1;i<=H;i++){
29             scanf("%s",mp[i]+1);
30         }
31         int sx,sy;
32         bool flag=0;
33         for(i=1;i<=H;i++){
34               for(j=1;j<=W;j++)
35                   if(mp[i][j]==‘@‘){
36                       sx=i;sy=j;
37                       flag=1;
38                       break;
39                   }
40             if(flag)break;
41         }
42         dfs(sx,sy);
43         printf("%d\n",ans);
44     }
45     return 0;
46 }