bzoj千题计划161：bzoj1589: [Usaco2008 Dec]Trick or Treat on the Farm 采集糖果

#include<cstdio>
#include<iostream>
#include<algorithm>

#define N 100001

using namespace std;

int to
;

int m;
int bl
,siz
;

int st
,top;
int id,dfn
,low
;
bool vis
;

int FRONT
,TO
,NXT
,TOT;
int in
;

int dp
;

void read(int &x)
{
x=0; char c=getchar();
while(!isdigit(c)) c=getchar();
while(isdigit(c)) { x=x*10+c-'0'; c=getchar(); }
}

void tarjan(int x)
{
dfn[x]=low[x]=++id;
vis[x]=true;
st[++top]=x;
if(!dfn[to[x]])
{
tarjan(to[x]);
low[x]=min(low[x],low[to[x]]);
}
else if(vis[to[x]]) low[x]=min(low[x],dfn[to[x]]);
if(dfn[x]==low[x])
{
++m;
while(st[top]!=x)
{
vis[st[top]]=false;
bl[st[top]]=m;
siz[m]++;
top--;
}
vis[x]=false;
bl[x]=m;
siz[m]++;
top--;
}
}

void add(int u,int v)
{
TO[++TOT]=v; NXT[TOT]=FRONT[u]; FRONT[u]=TOT;
in[v]++;
}

void topsort()
{
top=0;
for(int i=1;i<=m;++i)
{
if(!in[i]) st[++top]=i;
dp[i]=siz[i];
}
int now,t;
while(top)
{
now=st[top--];
for(int i=FRONT[now];i;i=NXT[i])
{
t=TO[i];
dp[t]+=dp[now];
in[t]--;
if(!in[t]) st[++top]=t;
}
}
}

int main()
{
int n;
read(n);
for(int i=1;i<=n;++i) read(to[i]);
for(int i=1;i<=n;++i)
if(!dfn[i]) tarjan(i);
for(int i=1;i<=n;++i)
if(bl[i]!=bl[to[i]]) add(bl[to[i]],bl[i]);
topsort();
for(int i=1;i<=n;++i) cout<<dp[bl[i]]<<'\n';
}