【POI2007】【Bzoj 1103】大都市meg

http://www.lydsy.com/JudgeOnline/problem.php?id=1103

在线查询某点到根节点的点权和,参考DFS序&欧拉序列,用树状数组维护即可O(nlogn)

// <meg.cpp> - Sun Oct  2 08:13:38 2016
// This file is made by YJinpeng，created by XuYike's black technology automatically.
// Copyright (C) 2016 ChangJun High School, Inc.
// I don't know what this program is.

#include <iostream>
#include <vector>
#include <algorithm>
#include <cstring>
#include <cstdio>
#include <cstdlib>
#include <cmath>
using namespace std;
const int MAXN=250010;
inline int gi() {
    register int w=0,q=0;register char ch=getchar();
    while((ch<'0'||ch>'9')&&ch!='-')ch=getchar();
    if(ch=='-')q=1,ch=getchar();
    while(ch>='0'&&ch<='9')w=w*10+ch-'0',ch=getchar();
    return q?-w:w;
}
int t,n,to[MAXN],ne[MAXN],fr[MAXN],b[MAXN],e[MAXN],c[MAXN];
void add(int u,int v){to[++t]=v;ne[t]=fr[u];fr[u]=t;}
void dfs(int x){
    b[x]=++t;
    for(int i=fr[x];i;i=ne[i])dfs(to[i]);
    e[x]=t+1;
}
void plu(int x,int u){
    for(;x<=n;x+=(-x)&x)c[x]+=u;
}
int src(int x){
    int ans=0;
    for(;x;x-=(-x)&x)ans+=c[x];
    return ans;
}
int main()
{
    n=gi();
    for(int i=1;i<n;i++){
        int u=gi(),v=gi();
        if(u>v)swap(u,v);
        add(u,v);
    }
    t=0;dfs(1);
    for(int i=2;i<=n;i++)
        plu(b[i],1),plu(e[i],-1);
    int m=gi()+n-1;
    while(m--){
        char ch=getchar();
        while(ch!='W'&&ch!='A')ch=getchar();
        if(ch=='A'){
            int u=gi(),v=gi();
            if(u>v)swap(u,v);
            plu(b[v],-1),plu(e[v],1);
        }else printf("%d\n",src(b[gi()]));
    }
    return 0;
}