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 }
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