hdu4185 Oil Skimming (最大匹配)

题目链接：http://acm.hdu.edu.cn/showproblem.php?pid=4185

题解：水平和竖直方向;有#相邻,连一条边，求最大匹配。

#include <cstdio>    
#include <cstring>    
#include <vector>    
#define MAXN 602 
#define MAXV 1000
using namespace std;    

vector<int> mp[MAXN];    
int from[MAXV],visited[MAXV];  
int matr[MAXN][MAXN];
char gra[MAXN][MAXN];

int match(int x)  
{  
	int i,temp,size;  
	size=mp[x].size();  
	for(i=0;i<size;++i)  
	{  
		temp=mp[x][i];  
		if(!visited[temp])  
		{  
			visited[temp]=1;  
			if(from[temp]==-1||match(from[temp]))  
			{  
				from[temp]=x;  
				return 1;  
			}  
		}  
	}  
	return 0;  
}  

int hungary(int n)
{
	int i,sum=0;
	memset(from,-1,sizeof(from));
	for(i=0;i<n;++i)
	{
		memset(visited,0,sizeof(visited));
		if(match(i))
			++sum;
	}
	return sum;
}
int main()
{
	int n,test,i,j,cnt,cases=0;
	scanf("%d",&test);
	while(test--)
	{
		scanf("%d",&n);
		cnt=0;
		for(i=0;i<n;++i)
		{
			scanf("%s",gra[i]);
			for(j=0;j<n;++j)
			{
				if(gra[i][j]=='#')
					matr[i][j]=cnt++;
			}
		}
		for(i=0;i<=cnt;++i)
		{
			mp[i].clear();
		}
		for(i=0;i<n;++i)
		{
			for(j=0;j<n;++j)
			{
				if(gra[i][j]!='#')
					continue;
				if(i>0&&gra[i-1][j]=='#')
					mp[matr[i][j]].push_back(matr[i-1][j]);
				if(i<n-1&&gra[i+1][j]=='#')
					mp[matr[i][j]].push_back(matr[i+1][j]);
				if(j>0&&gra[i][j-1]=='#')
					mp[matr[i][j]].push_back(matr[i][j-1]);
				if(j<n-1&&gra[i][j+1]=='#')
					mp[matr[i][j]].push_back(matr[i][j+1]);
			}
		}
		n=cnt;
		cnt=hungary(n);
		printf("Case %d: %d\n",++cases,cnt/2);
	}
	return 0;
}