zoj 2412 Farm Irrigation dfs

Description

Benny has a spacious farm land to irrigate. The farm land is a rectangle, and is divided into a lot of samll squares. Water pipes are placed in these squares. Different square has a different type of pipe. There are 11 types of pipes, which is marked from A to K, as Figure 1 shows.

Figure 1

Benny has a map of his farm, which is an array of marks denoting the distribution of water pipes over the whole farm. For example, if he has a map

ADCFJKIHE

then the water pipes are distributed like
Figure 2

Several wellsprings are found in the center of some squares, so water can flow along the pipes from one square to another. If water flow crosses one square, the whole farm land in this square is irrigated and will have a good harvest in autumn.

Now Benny wants to know at least how many wellsprings should be found to have the whole farm land irrigated. Can you help him?

Note: In the above example, at least 3 wellsprings are needed, as those red points in Figure 2 show.

Input

There are several test cases! In each test case, the first line contains 2 integers M and N, then M lines follow. In each of these lines, there are N characters, in the range of 'A' to 'K', denoting the type of water pipe over the corresponding square. A negative M or N denotes the end of input, else you can assume 1 <= M, N <= 50.

Output

For each test case, output in one line the least number of wellsprings needed.

Sample Input

2 2DKHF3 3ADCFJKIHE-1 -1

题意及分析：

这道题关于dfs方面不难。关键是不同管子之间联通 不好处理。

给出m x n 的农田。每个小格子有一个管子，管子有不同型号。如果农田之间通过管子可以相连，就看成一个整体。问这样的整体有多少个。

一个格子管子通向上面，如果下一个格子有朝下的接口，那么这两个格子就可以连通了。同理，接口朝左的管子，如果下一个格子有朝右的接口，那么联通也可以满足。其他情况也一样。用vis数组标记是否访问过，cnt计数。

AC代码：