树链剖分 探究

#include<bits/stdc++.h>
using namespace std;
const int maxn = 1e6+11;
int sz[maxn],dep[maxn],top[maxn],fa[maxn],son[maxn],dfn[maxn],pre[maxn];
//pre = ~ dfn
int to[maxn<<1],nxt[maxn<<1],head[maxn],tot,tot2;
void init(){memset(head,-1,sizeof head); tot=tot2=0;}
void add(int u,int v){
    to[tot]=v;nxt[tot]=head[u];head[u]=tot++;
    swap(u,v);
    to[tot]=v;nxt[tot]=head[u];head[u]=tot++;
}
void dfs1(int u,int p,int d){//sz fa son dep
    fa[u]=p;sz[u]=1;dep[u]=d;
    for(int i = head[u]; ~i; i = nxt[i]){
        int v=to[i];
        if(v==p)continue;
        dfs1(v,u,d+1);
        sz[u]+=sz[v]; //note
        if(!son[u]) son[u]=v;
        else if(sz[v]>sz[son[u]]) son[u]=v;
    }
}
void dfs2(int u,int tp){ //dfn pre | top
    pre[++tot2]=u;
    dfn[u]=tot2;
    top[u]=tp;
    if(son[u]) dfs2(son[u],tp); //只要有edge
    for(int i = head[u]; ~i; i = nxt[i]){
        int v=to[i];
        if(v==fa[u]||v==son[u]) continue;//not fa | hson
        dfs2(v,v);
    }
}
int main(){
    int u,v;
    init();
    while(cin>>u>>v){
        add(u,v);
        if(u==-1){
            dfs1(1,0,1);
            dfs2(1,1);
            cout<<tot2<<endl;
            for(int i = 1; i <= tot2; i++){
                cout<<i<<" "<<"sz "<<sz[i]<<" son "<<son[i]
                    <<" top "<<top[i]<<" dfn "<<dfn[i]<<" pre"
                    <<pre[i]<<endl;
            }
            for(int i = 1; i <= tot2; i++) cout<<(dfn[pre[i]]==i)<<endl;
            break;
        }
    }
    return 0;
}