BZOJ P1103 「POI2007」大都市meg【dfs序】【树状数组+差分】

#include <queue>
#include <cmath>
#include <cstdio>
#include <cstring>
#include <iostream>
#include <algorithm>
#define ll long long
#define rep(i,x,y) for(ll i=(x);i<=(y);i++)
#define repd(i,x,y) for(ll i=(x);i>=(y);i--)
using namespace std;
 
const ll N=3e5+5;
 
ll bit[N];
ll n,m,tim,in[N],out[N],deep[N];
ll cnt,to[N<<1],nxt[N<<1],head[N];
 
#define lowbit(x) (x&(-x))
 
inline ll read() {
    ll x=0;char ch=getchar();bool f=0;
    while(ch>'9'||ch<'0'){if(ch=='-')f=1;ch=getchar();}
    while(ch>='0'&&ch<='9'){x=(x<<1)+(x<<3)+ch-'0';ch=getchar();}
    return f?-x:x;
}
 
void ins(ll x,ll y) {
    to[++cnt]=y;nxt[cnt]=head[x];head[x]=cnt;
}
 
void dfs(ll x,ll fa) {
    in[x]=++tim;
    deep[x]=deep[fa]+1;
    for(int i=head[x];i;i=nxt[i]) if(to[i]!=fa) dfs(to[i],x);
    out[x]=tim;
}
 
void update(ll x,ll y) {
    for(;x<=n;x+=lowbit(x)) bit[x]+=y;
}
 
ll getsum(ll x) {
    ll ret=0;for(;x;x-=lowbit(x)) ret+=bit[x];return ret;
}
 
int main() {
    n=read();
    rep(i,1,n-1) {
        ll x=read(),y=read();
        ins(x,y),ins(y,x);
    }
     
    dfs(1,0);
     
    m=read();
    rep(i,1,n+m-1) {
        char ch[2];
        scanf("%s",ch+1);
        if(ch[1]=='W') {
            ll x=read();
            printf("%lld\n",deep[x]-1-getsum(in[x]));
        } else {
            ll x=read(),y=read();
            if(deep[x]<deep[y]) swap(x,y);
            update(in[x],1),update(out[x]+1,-1);
        }
    }
     
    return 0;
}