完美牛棚 - Java版本 - 使用了BufferedReader的更进一步封装

import java.util.*;
import java.io.*;

public class Main{

    static StreamTokenizer st = new StreamTokenizer(new BufferedReader(new InputStreamReader(System.in)));
    static PrintWriter pw = new PrintWriter(new OutputStreamWriter(System.out));
    static int nextInt() throws Exception{
        st.nextToken();
        return (int)st.nval;
    }
    static int[] h, e, ne, match;
    static boolean[] visited;
    static int idx;
    public static void main(String[] args) throws Exception{
        int n = nextInt();
        int m = nextInt();
        int res = 0;
        h = new int[n + 1];
        e = new int[n * m + 1];
        ne = new int[n * m + 1];
        match = new int[n + 1];
        visited = new boolean[m + 1];
        Arrays.fill(h , -1);
        for(int i = 1; i <= n; i ++){
            int s = nextInt();
            while (s -- > 0){
                int target=nextInt();
                add(i,target);
            }
        }

        for(int i = 1; i <= n; i ++){
            Arrays.fill(visited , false);
            if(find(i)) res ++;
        }

        pw.print(res);
        pw.flush();
    }
    static boolean find(int u){
        for(int i = h[u]; i != -1; i = ne[i]){
            int v = e[i];
            if(!visited[v]){
                visited[v] = true;
                if(match[v] == 0 || find(match[v])){
                    match[v] = u;
                    return true;
                }
            }
        }
        return false;
    }
    static void add(int a, int b){
        e[idx] = b;
        ne[idx] = h[a];
        h[a] = idx ++;
    }
}