codevs 1228 苹果树

dfs序+线段树

#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
#define maxv 100500
#define maxe 200500
using namespace std;
struct edge
{
    int v,nxt;
}e[maxe];
int n,m,x,y,nume=0,g[maxv];
int fath[maxv],w[maxv],mx[maxv],cnt=0;
int ls[maxv<<2],rs[maxv<<2],val[maxv<<2],tot=0,root;
char s[5];
void addedge(int u,int v)
{
    e[++nume].v=v;
    e[nume].nxt=g[u];
    g[u]=nume;
}
void dfs(int x,int father)
{
    w[x]=mx[x]=++cnt;
    for (int i=g[x];i;i=e[i].nxt)
    {
        int v=e[i].v;
        if (v!=father)
        {
            fath[v]=x;
            dfs(v,x);
            mx[x]=max(mx[x],mx[v]);
        }
    }
}
void build(int &now,int left,int right)
{
    now=++tot;val[now]=right-left+1;
    if (left==right) return;
    int mid=(left+right)>>1;
    build(ls[now],left,mid);
    build(rs[now],mid+1,right);
}
void pushup(int now)
{
    val[now]=val[ls[now]]+val[rs[now]];
}
int ask(int now,int left,int right,int l,int r)
{
    if ((left==l) && (right==r))
        return val[now];
    int mid=(left+right)>>1;
    if (r<=mid) return ask(ls[now],left,mid,l,r);
    else if (l>=mid+1) return ask(rs[now],mid+1,right,l,r);
    else return ask(ls[now],left,mid,l,mid)+ask(rs[now],mid+1,right,mid+1,r);
}
void modify(int now, int left,int right,int pos,int x)
{
    if ((left==right) && (right==pos))
    {
        val[now]=x;
        return;
    }
    int mid=(left+right)>>1;
    if (pos<=mid) modify(ls[now],left,mid,pos,x);
    else modify(rs[now],mid+1,right,pos,x);
    pushup(now);
}
int main()
{
    scanf("%d",&n);
    for (int i=1;i<=n-1;i++)
    {
        scanf("%d%d",&x,&y);
        addedge(x,y);
        addedge(y,x);
    }
    dfs(1,1);
    build(root,1,cnt);
    scanf("%d",&m);
    for (int i=1;i<=m;i++)
    {
        scanf("%s",s);
        if (s[0]=='C') 
        {
            scanf("%d",&x);
            int regis=ask(root,1,n,w[x],w[x]);
            if (regis==0) modify(root,1,n,w[x],1);
            else modify(root,1,n,w[x],0);
        }
        else
        {
            scanf("%d",&x);
            printf("%d
",ask(root,1,n,w[x],mx[x]));
        }
    }
    return 0;
}