题目描述

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.

输入

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)

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

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

Sample Output

4559613 解题思路： 深搜的方法解决，题目意思就是从@开始找.并与@连通，碰到#等于碰到了墙，题目很简单，@可以向四个方向上、下、左、右走，所以 用四个坐标标记出来，然后，再一一遍历，递归调用寻找，用一个30*30的数组标识此点有没有走过，避免走重复 程序代码：

#include 
       
        #include 
        
         using namespace std;int n,m,cot;char map[30][30];int to[4][2] = {
     {
     1,0},{
     0,1},{-1,0},{
     0,-1}};void dfs(int i,int j){    cot++;    map[i][j] = '#';    for(int k = 0; k<4; k++)    {        int x = i+to[k][0];        int y = j+to[k][1];        if(x
         
          =0 && y>=0 && map[x][y] == '.')            dfs(x,y);    }    return;}int main(){    int i,j,fi,fj;    while(~scanf("%d%d%*c",&m,&n)&&m&&n)    {        for(i = 0; i