典型迷宫。

#include<cstdio>
#include <cstring>

using namespace std;

int m, n,cnt, count;
char A[101][101];
int direction[4][2]={{1,0},{0,1},{0,-1},{-1,0}};

void dfs(int i, int j)
{
    if(i < 0|| j < 0|| i >= m|| j >= n || (A[i][j] != '.' && A[i][j] != '@'))
        return;
    else
    {
        A[i][j] = '#';
        cnt++;
        int di = i, dj = j;
        for(int q = 0; q < 4; ++q)
            dfs(di+ direction[q][0], dj+ direction[q][1]);
    }
}

int main()
{
    while(~scanf("%d%d", &n, &m) && (m+n))
    {
        cnt = 0;
        memset(A, 0, sizeof(A));
        for(int i = 0; i < m; ++i)
            scanf("%s", A[i]);

        for(int i = 0; i < m; ++i)
            for(int j = 0; j < n; ++j)
                if(A[i][j] == '@')
                    {
                        dfs(i, j);
                        break;
                    }

        printf("%d\n", cnt);
    }
}