车站分级 拓扑排序

#include <bits/stdc++.h>
#define pir pair<int,int>
using namespace std;
const int N = 1050;
int in[N],n,m,ans;
int book[N][N],s[N][N];
int vis[N];
queue<pir> q;
vector<int> g[N];
int read(){
	int x=0,dign=1;
	char c = getchar();
	while(c<'0'||c>'9'){
		if(c=='-')dign=-1;
		c = getchar();
	}
	while(c>='0'&&c<='9'){
		x = x*10+c-'0';
		c = getchar(); 
	}
	return x*dign;
} 
void spfa(){
	for(int i=1;i<=n;i++)if(!in[i])q.push(make_pair(i,1));//入度为0最低级1
	ans = 1;
	while(!q.empty()){
		int u = q.front().first;
		int val = q.front().second;q.pop();
		for(int i=0;i<g[u].size();i++){
			{
				in[g[u][i]]--;
				if(!in[g[u][i]])
				{q.push(make_pair(g[u][i],val+1));
				ans = max(val+1,ans);
				}
			}
		}	
	}	
}
int main()
{
	n = read(); m = read(); 
	for(int i=1;i<=m;i++){
		s[i][0] = read();
		memset(vis,0,sizeof(vis));
		for(int j=1;j<=s[i][0];j++){
			s[i][j] = read();
			vis[s[i][j]] = 1;//在s[i][j]点停靠 
		}
		for(int j=1;j<=s[i][0];j++)
		for(int k=s[i][1];k<=s[i][s[i][0]];k++)
		{
			if(vis[k])continue;
		{//对每条路 
			//起点到终点 
				
				if(!book[k][s[i][j]]){
					book[k][s[i][j]]=1;//连一条k到s[i][j]的路 
					in[s[i][j]]++;
					g[k].push_back(s[i][j]);
				}
			} 
		}
	}
		spfa();
		printf("%d\n",ans);
	return 0;
 }