POJ 1979 Red and Black (DFS)

Time limit:1000ms

Memory limit:30000k

Description

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

Write a program to count the number of black tiles which and 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 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 mans on a black tile (appears exactly once in a data set)

The end of the "input is indicated by a" consisting of two zeros.

Output

For each data set, your program should output a-line which contains the number of tiles to the the initial (including itself).

Sample Input

6 9

....#.

.....#

......

......

......

......

......

#@...#

.#.. #.

11 9

.#.........

.#.#######.

.#.#.....#.

.#.#.###.#.

.#.#.. @#.#.

.#.#####.#.

.#.......#.

.#########.

...........

11 6

.. #.. #.. #..

.. #.. #.. #..

.. #.. #.. ###

.. #.. #.. #@.

.. #.. #.. #..

.. #.. #.. #..

7 7

.. #.#..

.. #.#..

###.###

...@...

###.###

.. #.#..

.. #.#..

0 0

Sample Output

45

59

6

13

Source

Japan Domestic

A few days without a problem, first take the road water heat hot hands.

Complete code:

/*16ms,388kb*/
    
#include <cstdio>  
#include <cstring>  
    
char grid[25][25];  
BOOL vis[25][25];  
int cnt, x, y;  
    
void Dfs (int i, int j)  
{  
    if (grid[i][j] = = ' # ' | | vis[i][j]) return;  
    VIS[I][J] = true;  
    ++cnt;  
    DFS (I-1, j); DFS (i + 1, j); DFS (i, j-1); DFS (I, j + 1);  
}  
    
int main ()  
{  
    int i, J, xx, yy;  
    while (scanf ("%d%d\n", &x, &y), x)  
    {  
        memset (grid, ' # ', sizeof (GRID));  
        for (i = 1; I <= y; ++i)  
        {for  
            (j = 1; j <= x; ++j)  
            {  
                Grid[i][j] = GetChar ();  
                if (grid[i][j] = = ' @ ')  
                    xx = i, yy = j;  
            }  
            GetChar ();  
        }  
        memset (Vis, 0, sizeof (VIS));  
        CNT = 0;  
        DFS (xx, yy);  
        printf ("%d\n", CNT);  
    }  
    return 0;  
}

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