二分图最大匹配

来自裸题：过山车 HDU - 2063
代码：

import java.util.Arrays;
import java.util.Scanner;

public class Main
{   
    final static int maxn=1005;
    final static int maxx=2005;
    final static int INF =0x3f3f3f3f;
    static int cnt;
    static int head[]=new int[maxn];
    static int to[]=new int[maxx],next[]=new int[maxx];
    static void addEdge(int x,int y)
    {
        to[++cnt]=y;next[cnt]=head[x];head[x]=cnt;
        to[++cnt]=x;next[cnt]=head[y];head[y]=cnt;
    }
    static int match[]=new int[maxn];
    static boolean vis[]=new boolean[maxn];
    static void init()
    {
        Arrays.fill(match, 0);
        Arrays.fill(head, 0);
        cnt=0;
    }
    static boolean M(int u)
    {
        for(int i=head[u];i>0;i=next[i])
        {
            int v=to[i];
            if(vis[v])
                continue;
            vis[v]=true;
            if(match[v]==0||M(match[v]))
            {
                match[v]=u;
                match[u]=v;
                return true;
            }
        }
        return false;
    }
    public static void main(String[] args)
    {
        Scanner sc=new Scanner(System.in);
        for(;;)
        {
            int k=sc.nextInt();
            if(k==0)break;
            int n=sc.nextInt();
            int m=sc.nextInt();
            init();
            while(k-->0)
            {
                int x=sc.nextInt();
                int y=sc.nextInt()+n;
                addEdge(x,y);
            }
            int ans=0;
            for(int i=1;i<=n+m;i++)
            {
                if(match[i]==0)
                {
                    Arrays.fill(vis, false);
                    if(M(i))ans++;
                }
            }
            System.out.println(ans);
        }
    }
}