poj2226Muddy Fields——二分图匹配

#include<iostream>
#include<cstdio>
#include<cstring>
using namespace std;
int const MAXN=50005;
int R,C,bh[55][55][55][55],col[55][55],pre[MAXN],ans,cnt,head[MAXN],ct,bj;
char c[55][55],dc[55];
bool vis[MAXN];
struct N{
    int to,next;
    N(int t=0,int n=0):to(t),next(n) {}
}edge[MAXN*50];
void add(int x,int y)
{edge[++ct]=N(y,head[x]);head[x]=ct;}
bool dfs(int x)
{
    for(int i=head[x];i;i=edge[i].next)
    {
        int u=edge[i].to;
        if(!vis[u])
        {
            vis[u]=1;
            if(!pre[u]||dfs(pre[u]))
                {pre[u]=x;return 1;}
        }
    }
    return 0;
}
int main()
{
    scanf("%d%d",&R,&C);
    for(int i=1;i<=R;i++)
    {
        cin>>dc;
        for(int j=1;j<=C;j++)
            c[i][j]=dc[j-1];
    }    
    for(int i=1;i<=R;i++)
    {
        int j=1;
        while(j<=C)
        {
            if(c[i][j]==‘.‘){j++;continue;}
            cnt++;
            while(c[i][j]==‘*‘)col[i][j]=cnt,j++;
        }
    }
    bj=cnt;
    for(int j=1;j<=C;j++)
    {
        int i=1;
        while(i<=R)
        {
            if(c[i][j]==‘.‘){i++;continue;}
            cnt++;
            while(c[i][j]==‘*‘)
            {
                if(col[i][j])add(col[i][j],cnt);
                i++;
            }
        }
    }
    for(int i=1;i<=bj;i++)
    {
        memset(vis,0,sizeof vis);
        if(dfs(i))ans++;
    }
    printf("%d",ans);
    return 0;
}