洛谷 P1983 车站分级 拓扑排序

 

Code:

#include<cstdio>
#include<queue>
#include<algorithm>
#include<cstring>
using namespace std;
const int N=1000+1;
const int INF=10000+233;
queue<int>Q;
int A[N],ok[N],vis[N];
int G[N][N],d[N],degree[N];
int main()
{
	int n,m;
	scanf("%d%d",&n,&m);
	for(int cas=1;cas<=m;++cas)
	{
		memset(ok,0,sizeof(ok));
		int num;
		scanf("%d",&num);
		for(int i=1;i<=num;++i)
		{
			scanf("%d",&A[i]);
			ok[A[i]]=1;          
		}
		A[num+1]=INF;
		for(int i=A[1]+1;i<A[num];++i)
		{
			if(ok[i]==0)                  
			{
				for(int j=1;j<=num;++j) 
				{
					if(G[i][A[j]]==0)   
					{
						vis[i]=1;
						++degree[A[j]];
					    G[i][A[j]]=1;
					}
			    }
			}
		}
	}
	for(int i=1;i<=n;++i)if(degree[i]==0&&vis[i]==1){Q.push(i);d[i]=1;}
	int ans=0;
	while(!Q.empty())
	{
		int u=Q.front();Q.pop();
		for(int i=1;i<=n;++i)
		{
			if(G[u][i]==1)
			{
				--degree[i];
				if(degree[i]==0)
				{
					Q.push(i);
				}
				d[i]=d[u]+1;
				ans=max(d[i],ans);	
			}
		}
	}
	printf("%d",ans);
	return 0;
}