【CF343D】 Water Tree（树链剖分）

题目链接
树剖傻逼题，练练手好久没写树剖了。
查询忘记(pushdown)抓了好久虫。。
全文手写，一遍过。。。

#include <cstdio>
const int MAXN = 500010;
inline int read(){
    int s = 0, w = 1;
    char ch = getchar();
    while(ch < '0' || ch > '9'){ if(ch == '-') w = -1; ch = getchar(); }
    while(ch >= '0' && ch <= '9'){ s = s * 10 + ch - '0'; ch = getchar(); }
    return s * w;
}
struct Edge{
	int next, to;
}e[MAXN << 1];
int num, head[MAXN];
inline void Add(int from, int to){
	e[++num].to = to; e[num].next = head[from]; head[from] = num;
	e[++num].to = from; e[num].next = head[to]; head[to] = num;
}
int n, m;
#define lc (now << 1)
#define rc (now << 1 | 1)
int val[MAXN << 2], lazy[MAXN << 2];
inline void pushup(int now){
	val[now] = val[lc] && val[rc];
}
inline void pushdown(int now){
	if(lazy[now] == 1){
		lazy[lc] = lazy[rc] = 1;
		val[lc] = val[rc] = 0;
		lazy[now] = 0;
	}
	if(lazy[now] == 2){
		lazy[lc] = lazy[rc] = 2;
		val[lc] = val[rc] = 1;
		lazy[now] = 0;
	}
}
void Update(int now, int l, int r, int wl, int wr, int p){
	if(l > wr || r < wl) return;
	if(l >= wl && r <= wr){ val[now] = p; lazy[now] = p + 1; return; }
	pushdown(now);
	int mid = (l + r) >> 1;
	Update(lc, l, mid, wl, wr, p);
	Update(rc, mid + 1, r, wl, wr, p);
	pushup(now);
}
int Query(int now, int l, int r, int p){
	if(val[now]) return 1;
	if(l == r) return val[now];
	pushdown(now);
	int mid = (l + r) >> 1;
	if(p <= mid) return Query(lc, l, mid, p);
	return Query(rc, mid + 1, r, p);
}
int size[MAXN], son[MAXN], dep[MAXN], top[MAXN], pos[MAXN], ID, f[MAXN];
void dfs1(int u, int fa){
	dep[u] = dep[f[u] = fa] + 1;
	size[u] = 1;
	for(int i = head[u]; i; i = e[i].next)
	   if(e[i].to != fa){
	     dfs1(e[i].to, u);
	     size[u] += size[e[i].to];
	     if(size[e[i].to] > size[son[u]])
	       son[u] = e[i].to;
	   }
}
void dfs2(int u, int tp){
	top[u] = tp; pos[u] = ++ID;
	if(son[u]) dfs2(son[u], tp);
	for(int i = head[u]; i; i = e[i].next)
	   if(e[i].to != son[u] && e[i].to != f[u])
	     dfs2(e[i].to, e[i].to);
}
void root(int u){
	while(u){
		Update(1, 1, n, pos[top[u]], pos[u], 0);
		u = f[top[u]];
	}
}
void child(int u){
	Update(1, 1, n, pos[u], pos[u] + size[u] - 1, 1);
}
int a, b;
int main(){
	n = read();
	for(int i = 1; i < n; ++i) Add(read(), read());
	dfs1(1, 0); dfs2(1, 1);
	m = read();
	while(m--){
		a = read(); b = read();
		if(a == 1)
			child(b);
		if(a == 2)
			root(b);
		if(a == 3)
			printf("%d
", Query(1, 1, n, pos[b]));
	}
	return 0;
}