POJ练习深搜

#define _CRT_SECURE_NO_DEPRECATE
#include<iostream>
#include<cstdio>
#include<algorithm>
#define MAX 30
using namespace std;
char g[MAX][MAX];
int n, m, bx, by, totle;//行、列,起始坐标,总结果
int dx[4] = { -1, 1, 0, 0 }, dy[4] = { 0, 0, 1, -1 };
void dfs(int x, int y){
    g[x][y] = ‘#‘;
    for (int i = 0; i < 4; i++){
        int tx = x + dx[i], ty = y + dy[i];
        if (0 <= tx&&tx < n && 0 <= ty&&ty < m&&g[tx][ty] == ‘.‘){//0<= tx, 不要写成0<tx
            totle++;
            dfs(tx, ty);
        }
    }
}
int main()
{
    while (true){
        cin >> m >> n;
        if (m + n == 0)break;
        for (int i = 0; i < n; i++){
            for (int j = 0; j < m; j++){
                cin >> g[i][j];
                if (g[i][j] == ‘@‘){
                    bx = i;
                    by = j;
                }
            }
        }
        totle = 1;
        dfs(bx, by);
        cout << totle << endl;
    }
    return 0;
}