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线段树新功能get，太神奇了啊@-@

先遍历下树，时间戳记录下前后时间

子节点的前后时间都会在父节点的前后时间范围内

用线段树维护区间内深度最大和深度最小

#include <cstdio>
#include <cstring>
#include <cstdlib>
#include <string>
#include <iostream>
#include <algorithm>
#include <sstream>
#include <cmath>
using namespace std;
#include <queue>
#include <stack>
#include <set>
#include <vector>
#include <deque>
#include <map>
#define cler(arr, val)    memset(arr, val, sizeof(arr))
#pragma comment(linker, "/STACK:102400000,102400000")
typedef long long  LL;
const int MAXN = 102020;
const int MAXM = 240000;
const int INF = 0x3f3f3f3f;
const int mod = 1000000007;
#define lson l,m,rt<<1
#define rson m+1,r,rt<<1|1
int ti,maxx[MAXN<<2],minn[MAXN<<2],head[MAXN],tol,deep[MAXN];
struct node
{
    int v,next;
}edge[MAXM];
struct node1
{
    int t1,t2;
}tt[MAXN];
void init()
{
    cler(head,-1);tol=0;ti=0;
}
void addedge(int u,int v)
{
    edge[tol].v=v;edge[tol].next=head[u];head[u]=tol++;
}
void dfs(int u,int dep)
{
    deep[ti]=dep;
    for(int i=head[u];~i;i=edge[i].next)
    {
        int v=edge[i].v;
        tt[v].t1=++ti;
        dfs(v,dep+1);
        tt[v].t2=ti;
    }
}
void dfs1(int u,int dep)
{
    tt[u].t1=++ti;
    deep[ti]=dep;
    for(int i=head[u];~i;i=edge[i].next)
    {
        int v=edge[i].v;
        dfs1(v,dep+1);
    }
    tt[u].t2=ti;
}
void pushup(int rt)
{
    maxx[rt]=max(maxx[rt<<1],maxx[rt<<1|1]);
    minn[rt]=min(minn[rt<<1],minn[rt<<1|1]);
}
void build(int l,int r,int rt)
{
    if(l==r)
    {
        maxx[rt]=minn[rt]=deep[l];
        return ;
    }
    int m=(l+r)>>1;
    build(lson);
    build(rson);
    pushup(rt);
}
int query(int L,int R,int bb,int mm,int l,int r,int rt)
{
    if(L<=l&&r<=R&&maxx[rt]<=mm&&minn[rt]>=bb)
    {
        return r-l+1;
    }
    else if(minn[rt]>mm) return 0;
    else if(maxx[rt]<bb) return 0;
    int m=(l+r)>>1;
    int ans=0;
    if(L<=m) ans+=query(L,R,bb,mm,lson);
    if(R>m) ans+=query(L,R,bb,mm,rson);
    return ans;
}
int main()
{
#ifndef ONLINE_JUDGE
    freopen("in.txt", "r", stdin);
    //  freopen("out.txt", "w", stdout);
#endif
    int t,n,v,m,x,d;
    scanf("%d",&t);
    while(t--)
    {
        init();
        scanf("%d",&n);
        for(int i=2;i<=n;i++)
        {
            scanf("%d",&v);
            addedge(v,i);
        }
        ti=0;
        dfs1(1,0);
        build(1,n,1);
        scanf("%d",&m);
        while(m--)
        {
            scanf("%d%d",&x,&d);
            int ans=query(tt[x].t1,tt[x].t2,deep[tt[x].t1],deep[tt[x].t1]+d-1,1,n,1);
            printf("%d\n",ans);
        }
    }
    return 0;
}

【线段树】CSU 1414 Query on a Tree