记录编号	397262	评测结果	AAAAA
题目名称	2281.[HZOI 2015]白黑树	最终得分	100
用户昵称	AntiLeaf	是否通过	通过
代码语言	C++	运行时间	0.323 s
提交时间	2017-04-19 21:32:50	内存使用	21.10 MiB

#include<cstdio>
#include<cstring>
#include<algorithm>
#include<vector>
#include<queue>
using namespace std;
const int maxn=200010;
void dfs(int);
void RMQ_init();
int LCA(int,int);
template<typename cmp>struct binary_heap{
	priority_queue<int,vector<int>,cmp>q1,q2;
	void push(int x){q1.push(x);}
	void erase(int x){q2.push(x);}
	int top(){
		while(!q2.empty()&&q1.top()==q2.top()){
			q1.pop();
			q2.pop();
		}
		return q1.top();
	}
	bool empty(){
		while(!q2.empty()&&q1.top()==q2.top()){
			q1.pop();
			q2.pop();
		}
		return q1.empty();
	}
};
vector<int>G[maxn];
int f[maxn][20],log_tbl[maxn];
int p[maxn],d[maxn],dfn[maxn],tim=0;
struct cmp1{cmp1(){}bool operator()(int x,int y){return dfn[x]<dfn[y];}};
binary_heap<cmp1>heap1;
struct cmp2{cmp2(){}bool operator()(int x,int y){return dfn[x]>dfn[y];}};
binary_heap<cmp2>heap2;
bool col[maxn]={false};
char c;
int n,m,x,y,last;
int main(){
	freopen("C_Tree.in","r",stdin);
	freopen("C_Tree.out","w",stdout);
	scanf("%d%d",&n,&m);
	for(int i=1;i<n;i++){
		scanf("%d%d",&x,&y);
		G[x].push_back(y);
		G[y].push_back(x);
	}
	dfs(1);
	RMQ_init();
	while(m--){
		scanf(" %c%d",&c,&x);
		if(c=='M'){
			if(col[x]){
				heap1.erase(x);
				heap2.erase(x);
			}
			else{
				heap1.push(x);
				heap2.push(x);
			}
			col[x]^=true;
		}
		else{
			if(heap1.empty())printf("-1\n");
			else{
				int u=LCA(x,heap1.top()),v=LCA(x,heap2.top());
				printf("%d\n",d[u]<d[v]?u:v);
			}
		}
	}
	return 0;
}
void dfs(int x){
	f[tim][0]=last;
	last=x;
	dfn[x]=++tim;
	d[x]=d[p[x]]+1;
	for(int i=0;i<(int)G[x].size();i++)if(G[x][i]!=p[x]){
		p[G[x][i]]=x;
		dfs(G[x][i]);
	}
	last=p[x];
}
void RMQ_init(){
	log_tbl[0]=-1;
	for(int i=1;i<n;i++)log_tbl[i]=log_tbl[i>>1]+1;
	for(int j=1;(1<<j)<n;j++)for(int i=1;i+(1<<j)-1<n;i++)
		f[i][j]=(d[f[i][j-1]]<d[f[i+(1<<(j-1))][j-1]]?f[i][j-1]:f[i+(1<<(j-1))][j-1]);
}
int LCA(int l,int r){
	if(l==r)return l;
	l=dfn[l];r=dfn[r];
	if(l>r)swap(l,r);
	r--;
	int k=log_tbl[r-l+1];
	return d[f[l][k]]<d[f[r-(1<<k)+1][k]]?f[l][k]:f[r-(1<<k)+1][k];
}