POJ 1979 Red and Black

#include <iostream>

using namespace std;

#define MAXNUM 25

int counter = 0;
char data[MAXNUM][MAXNUM];
int visit[MAXNUM][MAXNUM];
int dir[4][2] = {{0,-1},{1,0},{0,1},{-1,0}};

void DFS(int row,int col,int m, int n);

int main()
{
int m = 0;
int n = 0;
int bx = 0;
int by = 0;
while(true)
{
cin>>n>>m;
if(m == 0 && n == 0)
{
break;
}
counter = 0;
memset(visit,0,sizeof(visit));
memset(data,0,sizeof(data));
for(int i = 0; i < m; i++)
{
for(int j = 0; j < n; j++)
{
cin>>data[i][j];
if(data[i][j] == '@')
{
bx = i;
by = j;
}
}
}
visit[bx][by] = 1;
counter++;
DFS(bx,by,m,n);
cout<<counter<<endl;
}
return 0;
}

void DFS(int row,int col,int m, int n)
{
//深度优先搜索
int r = 0;
int c = 0;

for(int i = 0; i < 4; i++)    //四个方向
{
r = row + dir[i][0];
c = col + dir[i][1];
if(r >= 0 && r < m && c >= 0 && c < n    //未越界
&& data[r][c] != '#'                 //不是墙
&& visit[r][c] == 0)                 //没走过
{
counter++;
visit[r][c] = 1;
DFS(r,c,m,n);
}
}
}