E88 换根DP CF708C Centroids

视频链接：E88 换根DP CF708C Centroids_哔哩哔哩_bilibili

 

 

参看：E34 树形DP 树的中心 - 董晓 - 博客园

CF708C Centroids - 洛谷 | 计算机科学教育新生态 (luogu.com.cn)

// 换根DP O(n)
#include<bits/stdc++.h>
using namespace std;

int read(){
  int x=0,s=1;char c=getchar();
  while(c<'0'||c>'9')s=(c=='-')?-1:1,c=getchar();
  while(c>='0'&&c<='9') x=x*10+c-'0',c=getchar();
  return x*s;
}
const int N=400005;
vector <int> e[N];

int n,sz[N],mx[N],mx2[N],f[N],g[N],ans[N];

void dfs(int u,int fa){
  sz[u]=1;
  for(int v:e[u]){
    if(v==fa) continue;
    dfs(v,u);
    sz[u]+=sz[v];
    if(sz[mx[u]]<sz[v]) mx2[u]=mx[u],mx[u]=v;
    else if(sz[mx2[u]]<sz[v]) mx2[u]=v;
    f[u]=max(f[u],f[v]);
  }
  if(sz[u]<=n/2) f[u]=sz[u];
}
void dfs2(int u,int fa){
  for(int v:e[u]){
    if(v==fa) continue;
    if(n-sz[v]<=n/2) g[v]=n-sz[v];
    else if(v!=mx[u])g[v]=max(g[u],f[mx[u]]);
    else g[v]=max(g[u],f[mx2[u]]);
    dfs2(v,u);
  }
  if(sz[u]>n/2) ans[u]=(sz[mx[u]]-f[mx[u]]<=n/2);
  else ans[u]=(n-sz[u]-g[u]<=n/2);
}
signed main(){
  n=read();
  for(int i=1,u,v;i<n;i++){
    u=read(),v=read();
    e[u].push_back(v);
    e[v].push_back(u);
  }
  dfs(1,0);
  dfs2(1,0);
  for(int i=1;i<=n;i++) printf("%d ",ans[i]);
}