BZOJ：1103: [POI2007]大都市meg

#include<iostream>
#include<cstdio>
#include<cstring>
using namespace std;
const int maxn=300000;
const int inf=1000000000;

int n,m;

int cntedge;
int head[maxn];
int nex[maxn<<1],to[maxn<<1];
int addedge(int x,int y){
	nex[++cntedge]=head[x];
	to[cntedge]=y;
	head[x]=cntedge;
}

int idx[maxn],father[maxn],siz[maxn];
int depth[maxn];
int temp;
int dfs(int now,int fa){
	depth[now]=depth[fa]+1;
	father[now]=fa;
	idx[now]=(++temp);
	siz[now]=1;
	for(int i=head[now];i;i=nex[i]){
		if(to[i]==fa)continue;
		dfs(to[i],now);
		siz[now]+=siz[to[i]];
	}
}

int f[maxn][21];
int Lcainit(){
	for(int i=1;i<=n;++i)f[i][0]=father[i];
	for(int j=1;j<=20;++j){
		for(int i=1;i<=n;++i){
			f[i][j]=f[f[i][j-1]][j-1];
		}
	}
}

int Getlca(int u,int v){
	if(depth[u]<depth[v])swap(u,v);
	for(int j=20;j>=0;--j){
		if(depth[f[u][j]]>=depth[v])u=f[u][j];
	}
	if(u==v)return u;
	for(int j=20;j>=0;--j){
		if(f[u][j]!=f[v][j]){
			u=f[u][j];
			v=f[v][j];
		}
	}
	return father[u];
}

int c[maxn];
inline int lowbit(int x){
	return x&(-x);
}
int add(int x,int val){
	while(x<=n){
		c[x]+=val;
		x+=lowbit(x);
	}
}
int query(int x){
	int ret=0;
	while(x){
		ret+=c[x];
		x-=lowbit(x);
	}
	return ret;
}

int main(){
	scanf("%d",&n);
	for(int i=1;i<=n-1;++i){
		int x,y;
		scanf("%d%d",&x,&y);
		addedge(x,y);
		addedge(y,x);
	}
	dfs(1,0);
	scanf("%d",&m);
	m=n+m-1;
	while(m--){
		char opty=getchar();
		while((opty!=‘W‘)&&(opty!=‘A‘))opty=getchar();
		int x,y;
		if(opty==‘A‘){
			scanf("%d%d",&x,&y);
			if(depth[x]>depth[y])swap(x,y);
			add(idx[y],1);
			add(idx[y]+siz[y],-1);
		}else{
			scanf("%d",&x);
			printf("%d\n",depth[x]-1-query(idx[x]));
		}
	}
	return 0;
}