(简单递归3.2.1)POJ 1979 Red and Black(利用回溯法来扫图)

/*
 * POJ_1979.cpp
 *
 *  Created on: 2013年10月24日
 *      Author: Administrator
 */

#include <iostream>
#include <cstdio>
#include <cstring>

using namespace std;

const int maxn = 25;

int n,m;
char map[maxn][maxn];//瓷砖图
int visited[maxn][maxn];//用来标记是否访问过
int ans;

//利用回溯法来扫图
void search(int row,int col){
	if(row < 0 || row >= m || col < 0 || col >= n || map[row][col] == '#' || visited[row][col]){
		return ;
	}

	visited[row][col] = true;
	ans++;

	search(row-1,col);
	search(row+1,col);
	search(row,col-1);
	search(row,col+1);
}



int main(){
	while(scanf("%d%d",&n,&m)!=EOF,n||m){
		ans = 0;
		memset(visited,false,sizeof(visited));

		int i,j;
		int row ,col;
		for(i = 0 ; i < m ; ++i){
			for(j = 0 ; j < n ; ++j){
				scanf(" %c",&map[i][j]);
				if(map[i][j] == '@'){
					row = i;
					col = j;
				}
			}


		}

		search(row,col);

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

	return 0;
}