poj 1979 Red and Black（dfs）

 1 #include <cstdio>
 2 int dir[4][2] = {{0,1},{1,0},{0,-1},{-1,0}};
 3 char map[21][21];
 4 int n,m;
 5 int result;
 6 
 7 void DFS(int sx, int sy)
 8 {
 9     int tx,ty;
10     for(int k = 0; k < 4; ++k)
11     {
12         tx = sx + dir[k][0];
13         ty = sy + dir[k][1];
14 
15         if(tx < 0 || ty < 0 || tx >= m || ty >= n)
16             continue;
17 
18         if(map[tx][ty] == ‘.‘)
19         {
20             ++result;
21             map[tx][ty] = ‘#‘;
22             DFS(tx,ty);
23         }
24     }
25 }
26 
27 int main()
28 {
29     int sx,sy;
30     while(scanf("%d %d",&n,&m) && n+m)
31     {
32         result = 1;
33         for(int i = 0; i < m; ++i)
34             for(int j = 0; j < n; ++j)
35             {
36                 scanf(" %c",&map[i][j]);
37                 if(map[i][j] == ‘@‘)
38                 {
39                     sx = i;
40                     sy = j;
41                 }
42             }
43 
44         DFS(sx,sy);
45         printf("%d\n",result);
46     }
47 }