Red and Black HDU 1312

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 20. 

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) 

 

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

     
     
     
     

      
      
      
      6 9
....#.
.....#
......
......
......
......
......
#@...#
.#..#.
11 9
.#.........
.#.#######.
.#.#.....#.
.#.#.###.#.
.#.#..@#.#.
.#.#####.#.
.#.......#.
.#########.
...........
11 6
..#..#..#..
..#..#..#..
..#..#..###
..#..#..#@.
..#..#..#..
..#..#..#..
7 7
..#.#..
..#.#..
###.###
...@...
###.###
..#.#..
..#.#..
0 0 
     
     
     
     

 

Sample Output

     
     
     
     

      
      
      
      45
59
6
13 
     
     
     
     

 

#include<stdio.h>
char a[30][30];
int n,m,z;
int b[4][2]= {{1,0},{0,1},{-1,0},{0,-1}};
void dfs(int i,int j)
{
    z++;
    a[i][j]='#';
    for(int w=0; w<4; w++)
    {
        int x=i+b[w][0];
        int y=j+b[w][1];

        if(x<n&&y<m&&x>=0&&y>=0&&a[x][y]=='.')
            dfs(x,y);
    }
    return ;
}
int main()
{
    while(scanf("%d%d*c",&m,&n)!=EOF)
    {
        if(m==0&&n==0)
            break;
        int i,j,pi,qi;
        for(i=0; i<n; i++)
            scanf("%s",a[i]);
       getchar();
        for(i=0; i<n; i++)
        {
            for(j=0; j<m; j++)
            {
               //scanf("%c",&a[i][j]);
                if(a[i][j]=='@')
                {
                    pi=i;
                    qi=j;
                    break;
                }
            }
            //getchar ();
        }
        z=0;
        dfs(pi,qi);
        printf("%d\n",z);

    }
    return 0;
}