poj 1979 Red and Black（dfs水题）

Description

There is a rectangular room, covered with square tiles. Each tile is colored either red or black. A man is standing on a black tile. From a tile, he can move to one of four adjacent tiles. But he can't move on red tiles, he can move only on black tiles. 

Write a program to count the number of black tiles which he can reach by repeating the moves described above. 

Input

The input consists of multiple data sets. A data set starts with a line containing two positive integers W and H; W and H are the numbers of tiles in the x- and y- directions, respectively. W and H are not more than . 

There are H more lines in the data set, each of which includes W characters. Each character represents the color of a tile as follows. 

'.' - a black tile
'#' - a red tile
'@' - a man on a black tile(appears exactly once in a data set)
The end of the input is indicated by a line consisting of two zeros. 

Output

For each data set, your program should output a line which contains the number of tiles he can reach from the initial tile (including itself).

Sample Input

....#.
.....#
......
......
......
......
......
#@...#
.#..#.

.#.........
.#.#######.
.#.#.....#.
.#.#.###.#.
.#.#..@#.#.
.#.#####.#.
.#.......#.
.#########.
...........

..#..#..#..
..#..#..#..
..#..#..###
..#..#..#@.
..#..#..#..
..#..#..#..

..#.#..
..#.#..
###.###
...@...
###.###
..#.#..
..#.#..
 

Sample Output

Source

Japan 2004 Domestic

 

 

 

 #include<iostream>
 #include<cstdio>
 #include<cstring>
 using namespace std;
 #define N 26
 int n,m;
 char mp[N][N];
 int x,y;
 int vis[N][N];
 int ans;
 int dirx[]={,,-,};
 int diry[]={-,,,};
 void dfs(int sx,int sy){
     for(int i=;i<;i++){
         int xx=sx+dirx[i];
         int yy=sy+diry[i];
         if(vis[xx][yy]) continue;
         if(mp[xx][yy]=='#') continue;
         if(xx< || xx>=n || yy< || yy>=m) continue;
         vis[xx][yy]=;
         ans++;
         dfs(xx,yy);
     }
 }
 int main()
 {
     while(scanf("%d%d",&m,&n)== && n+m){
         for(int i=;i<n;i++){
             scanf("%s",mp[i]);
             for(int j=;j<m;j++){
                 if(mp[i][j]=='@'){
                     x=i;y=j;
                 }
             }
         }
         memset(vis,,sizeof(vis));
         ans=;
         vis[x][y]=;
         dfs(x,y);
         printf("%d\n",ans);

     }
     return ;
 }