hdu 1198 Farm Irrigation

最新推荐文章于 2020-11-23 22:35:42 发布

原创最新推荐文章于 2020-11-23 22:35:42 发布 · 475 阅读

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本博客探讨了如何通过最少数量的水源点确保整个农田得到灌溉的问题，利用图论知识解决实际农业灌溉问题。

Farm Irrigation

Time Limit: 2000/1000 MS (Java/Others) Memory Limit: 65536/32768 K (Java/Others)
Total Submission(s): 4328 Accepted Submission(s): 1871

Problem 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

ADC
FJK
IHE

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 2
DK
HF

3 3
ADC
FJK
IHE

-1 -1

Sample Output

2
3

题意：寻找有几个互不相通的农场！

AC代码

#include <iostream>
using namespace std;
char a[11][5]={"1010","1001","0110","0101","1100","0011","1011","1110","0111","1101","1111"};
char map[51][51];
int father[2510];
int m,n;
int find(int x)
{
	if(x!=father[x])
		father[x]=find(father[x]);
	return father[x];
}
void Union(int a,int b)
{
	a=find(a);
	b=find(b);
	if(a!=b)
		father[a]=b;
}
void judge(int i,int j)//判断“左”，“上”是否相通，是就合并
{
	if(j>0&&a[map[i][j]-'A'][2]=='1'&&a[map[i][j-1]-'A'][3]=='1')
		Union(i*n+j,i*n+j-1);
	
	if(i>0&&a[map[i][j]-'A'][0]=='1'&&a[map[i-1][j]-'A'][1]=='1')
		Union(i*n+j,(i-1)*n+j);
}
int main()
{
   int i,j,count;
   while(scanf("%d%d",&m,&n)!=EOF)
   {
	   if(m==-1&&n==-1)
		   break;
	   for(i=0;i<m*n;i++)
		   father[i]=i;
	   for(i=0;i<m;i++)
		   scanf("%s",map[i]);
	   for(i=0;i<m;i++)
		   for(j=0;j<n;j++)
				judge(i,j);
		   count=0;
		   for(i=0;i<m*n;i++)
				   if(father[i]==i)
					   count++;
					printf("%d\n",count);


   }
	return 0;
}

谢谢阅读！