简单搜索RED&BLACK题解

简单搜索RED&BLACK题解

原题如下
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.
Input
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)
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
…#.
…#
…
…
…
…
…
#@…#
.#…#.
0 0
Sample Output
45
翻译如下（百度翻译）
有一个长方形的房间，上面铺着方砖。每一块瓷砖都是红色或黑色的。一个男人站在一块黑色的瓷砖上。从一个瓷砖，他可以移动到四个相邻瓷砖之一。但他不能在红瓦上移动，只能在黑瓦上移动。编写一个程序，通过重复上述动作来计算他可以达到的黑色瓷砖的数量。

输入
输入由多个数据集组成。数据集以包含两个正整数W和H的行开头；W和H分别是x和y方向上的平铺数。W和H不超过20。
数据集中还有H行，每行包含W个字符。每个字符代表一个瓷砖的颜色，如下所示。

‘.’-一块黑色的瓷砖

“35;”-红色瓷砖

“@”-一个站在黑色瓷砖上的人（在数据集中只出现一次）

输出
对于每个数据集，您的程序应该输出一行，其中包含他可以从初始平铺（包括其本身）到达的平铺数。

思路：可以用while循环输入，找到‘@’的位置，然后进行DFS搜索（注意先用两个数组判定方向）

AC代码如下：

#include <iostream>
using namespace std;
int ans=1;