https://www.luogu.org/problemnew/show/P1983

题解：拓扑排序

参考文章：https://blog.csdn.net/weixin_43272781/article/details/87918994

/*
*@Author:   STZG
*@Language: C++
*/
#include <bits/stdc++.h>
#include<iostream>
#include<algorithm>
#include<cstdlib>
#include<cstring>
#include<cstdio>
#include<string>
#include<vector>
#include<bitset>
#include<queue>
#include<deque>
#include<stack>
#include<cmath>
#include<list>
#include<map>
#include<set>
//#define DEBUG
#define RI register int
using namespace std;
typedef long long ll;
//typedef __int128 lll;
const int N=1000+10;
const int M=100000+10;
const int MOD=1e9+7;
const double PI = acos(-1.0);
const double EXP = 1E-8;
const int INF = 0x3f3f3f3f;
int t,n,m,k,q;
int ans,cnt,flag,temp,sum;
int a[N];
bool vis[N][N];
bool is[N];
char str;
struct node{};
int in[N];
int dep[N];
vector<int>G[N];
void topo(){
    queue<int>q;
    for(int i=1;i<=n;i++){
        if(!in[i]){
            q.push(i);
            dep[i]=1;
        }
    }
    while(!q.empty()){
        int u=q.front();
        q.pop();
        for(int i=0,j=G[u].size();i<j;i++){
            int v=G[u][i];
            dep[v]=dep[u]+1;
            ans=max(ans,dep[v]);
            in[v]--;
            if(!in[v])
                q.push(v);
        }
    }

}
int main()
{
#ifdef DEBUG
    freopen("input.in", "r", stdin);
    //freopen("output.out", "w", stdout);
#endif
    //ios::sync_with_stdio(false);
    //cin.tie(0);
    //cout.tie(0);
    //scanf("%d",&t);
    //while(t--){
    scanf("%d%d",&n,&m);
    for(int i=1;i<=m;i++){
        scanf("%d",&k);
        memset(a,0,sizeof(a));
        memset(is,0,sizeof(is));
        for(int j=1;j<=k;j++){
            scanf("%d",&a[j]);
            is[a[j]]=1;
        }
        for(int j=a[1];j<=a[k];j++){
            if(!is[j]){
                for(int p=1;p<=n;p++){
                   if(!vis[j][a[p]]){
                        in[a[p]]++;
                        G[j].push_back(a[p]);
                        vis[j][a[p]]=1;
                   }
                }
            }
        }
    }
    topo();
    cout<<ans<<endl;
    //}

#ifdef DEBUG
    printf("Time cost : %lf s\n",(double)clock()/CLOCKS_PER_SEC);
#endif
    //cout << "Hello world!" << endl;
    return 0;
}