随笔 - 0  文章 - 5  trackbacks - 0
<2025年6月>
25262728293031
1234567
891011121314
15161718192021
22232425262728
293012345

常用链接

留言簿(2)

文章分类

文章档案

教育

信息学奥赛

有用网站

在线OJ

专题测试

租房信息

搜索

  •  

最新评论

Antenna Placement
Time Limit: 1000MS Memory Limit: 65536K
Total Submissions: 3993 Accepted: 1954

Description

The Global Aerial Research Centre has been allotted the task of building the fifth generation of mobile phone nets in Sweden. The most striking reason why they got the job, is their discovery of a new, highly noise resistant, antenna. It is called 4DAir, and comes in four types. Each type can only transmit and receive signals in a direction aligned with a (slightly skewed) latitudinal and longitudinal grid, because of the interacting electromagnetic field of the earth. The four types correspond to antennas operating in the directions north, west, south, and east, respectively. Below is an example picture of places of interest, depicted by twelve small rings, and nine 4DAir antennas depicted by ellipses covering them.

Obviously, it is desirable to use as few antennas as possible, but still provide coverage for each place of interest. We model the problem as follows: Let A be a rectangular matrix describing the surface of Sweden, where an entry of A either is a point of interest, which must be covered by at least one antenna, or empty space. Antennas can only be positioned at an entry in A. When an antenna is placed at row r and column c, this entry is considered covered, but also one of the neighbouring entries (c+1,r),(c,r+1),(c-1,r), or (c,r-1), is covered depending on the type chosen for this particular antenna. What is the least number of antennas for which there exists a placement in A such that all points of interest are covered?

Input

On the first row of input is a single positive integer n, specifying the number of scenarios that follow. Each scenario begins with a row containing two positive integers h and w, with 1 <= h <= 40 and 0 < w <= 10. Thereafter is a matrix presented, describing the points of interest in Sweden in the form of h lines, each containing w characters from the set ['*','o']. A '*'-character symbolises a point of interest, whereas a 'o'-character represents open space.

Output

For each scenario, output the minimum number of antennas necessary to cover all '*'-entries in the scenario's matrix, on a row of its own.

Sample Input

2
7 9
ooo**oooo
**oo*ooo*
o*oo**o**
ooooooooo
*******oo
o*o*oo*oo
*******oo
10 1
*
*
*
o
*
*
*
*
*
*

Sample Output

17
5

Source


题目大意:给出一张图,图中元素为’*'或者’o'。其中,相连的两个’*’可以划入一个圈中。问至少需要几个圈将所有的’*'画起来。
输入
  第一行为数据组数n
  以下共有n组数据
  每组数据第一行为两个数 x,y
  表示 是x行y列 的矩阵
输出
  最少圈数

posted on 2011-10-26 23:34 龙在江湖 阅读(164) 评论(0)  编辑 收藏 引用 所属分类: 图论竞赛题解_POJ