HDU 1312

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 1 #include<stdio.h>
 2 #include<stdlib.h>
 3 #include<string.h>
 4 以前用BFS写过，这次改用DFS写发现DFS掌握的不好，挑了好久才过，今下午才AC了两道题，还要加紧练习DFS！
 5 int row,col,count,vis[21][21];
 6 char map[21][21];
 7 int dx[] = {0,0,-1,1};
 8 int dy[] = {1,-1,0,0};
 9 void DFS(int x,int y)
10 {
11     int sx,sy,i;
12     vis[x][y] = 1;   
13      for(i=0; i<4; i++)
14      {
15         sx = x + dx[i]; 
16         sy = y + dy[i];
17         if(!vis[sx][sy]&&sx>=0&&sx<row&&sy>=0&&sy<col&&map[sx][sy]!='#')
18         {
19             vis[sx][sy] = 1;
20             if(map[sx][sy]=='.')
21               count++;          
22             DFS(sx,sy);
23         }
24      } 
25      return ;
26 }
27 
28 int main()
29 {
30     int i,j,bx,by;
31     
32     while(scanf("%d%d",&col,&row)&&col&&row)
33     {
34        getchar();                            
35        for(i=0; i<row; i++) 
36        {
37           for(j=0; j<col; j++)
38           {       
39             scanf("%c",&map[i][j]);
40           }      
41            getchar();
42        }
43        for(i=0; i<row; i++)
44         for(j=0; j<col; j++)
45          {
46            if(map[i][j]=='@')
47            {
48                bx = i;
49                by = j;
50            }
51          }  
52        count = 1;
53        memset(vis,0,sizeof(vis));
54        vis[bx][by] = 1;
55        DFS(bx,by);
56        printf("%d\n",count);
57         
58     }
59    return 0;    
60 }