Tarjan+Topo......

这份117行的绿题代码招来了9个WA以及一旁机房大佬的不屑

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#include<iostream>
#include<cstdio>
#include<cstring>
#include<stack>
#include<queue>
using namespace std;
#define signed register int
#define N 1000100
int n,m,num,head[N],head2[N],dfn[N],low[N],sta[N],sta_max[N],in[N],visn,stan,k;//stan 缩点后的序号 in 缩点后每点的入度 
bool vis[N];
stack<int>s;
queue<int>q;
struct Edge{
	int to;
	int next;
}edge[N];
struct Edge2{
	int to;
	int next;
}edge2[N];//缩点后建立反向边 
inline void AddEdge1(int x,int y)
{
	edge[++num].to=y;
	edge[num].next=head[x];
	head[x]=num;
}
inline void AddEdge2(int x,int y)
{
	edge2[++num].to=y;
	edge2[num].next=head2[x];
	head2[x]=num;
}
inline void Tarjan(int u)
{
	dfn[u]=low[u]=++visn;
	s.push(u);vis[u]=true;
	for(signed i=head[u];i;i=edge[i].next)
	{
		int v=edge[i].to;
		if(!vis[v])
		{
			Tarjan(v);
			low[u]=min(low[u],low[v]);
		}
		else if(!sta[v])
		low[u]=min(low[u],dfn[v]);
	} 
	if(low[u]==dfn[u])
	{
		sta[u]=++stan;
		while(s.top()!=u)
		{
			sta[s.top()]=stan;
			sta_max[stan]=max(sta_max[stan],s.top());
			s.pop();
		}
		sta_max[stan]=max(sta_max[stan],s.top());
		s.pop();
	}
}
inline void Topo()
{
	for(signed i=1;i<=stan;i++)
	if(!in[i])q.push(i);
	while(!q.empty())
	{
		int fro=q.front();q.pop();
		for(signed i=head2[fro];i;i=edge2[i].next)
		{
			int to=edge2[i].to;
			sta_max[to]=max(sta_max[to],sta_max[fro]);
			in[to]--;
			if(!in[to])q.push(to);
		}
	}
}
inline void starts()
{
	memset(head,0,sizeof(head));
	memset(head2,0,sizeof(head));
	memset(dfn,0,sizeof(dfn));
	memset(vis,false,sizeof(vis));
	memset(sta_max,0,sizeof(sta_max)); 
	memset(in,0,sizeof(in));
}//初始化 
int main()
{
	freopen("P3916.in","r",stdin);
	freopen("P3916.out","w",stdout);
	ios::sync_with_stdio(false);
	starts();
	cin>>n>>m;
	for(signed i=1;i<=m;i++)
	{
		int x,y;
		cin>>x>>y;
		AddEdge1(x,y);
	}
	for(signed i=1;i<=n;i++)
	if(!dfn[i])Tarjan(i);
	for(signed k=1;k<=n;k++)
	{
		for(signed i=head[k];i;i=edge[i].next)
		{
			int to=edge[i].to;
			if(sta[k]!=sta[to])
			{
				AddEdge2(to,k);
				in[sta[k]]++;
			}
		} 
	}
	Topo();
	for(signed i=1;i<=n;i++)
	cout<<sta_max[sta[i]]<<' ';
	return 0;
}

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