luogu3203 [HNOI2010]弹飞绵羊

lct裸题

#include <iostream>
#include <cstdio>
using namespace std;
int n, ski[200005], m, uu, vv, opt, siz[200005], ch[200005][2], fa[200005];
int rev[200005];
bool isRoot(int x){
	return ch[fa[x]][0]!=x && ch[fa[x]][1]!=x;
}
bool getW(int x){
	return ch[fa[x]][1]==x;
}
void pushDown(int x){
	if(rev[x]){
		swap(ch[x][0], ch[x][1]);
		rev[ch[x][0]] ^= 1;
		rev[ch[x][1]] ^= 1;
		rev[x] = 0;
	}
}
void upd(int x){
	siz[x] = siz[ch[x][0]] + siz[ch[x][1]] + 1;
}
void xf(int x){
	if(!isRoot(x))	xf(fa[x]);
	pushDown(x);
}
void rotate(int x){
	int old=fa[x], oldf=fa[old], w=getW(x);
	if(!isRoot(old))	ch[oldf][ch[oldf][1]==old] = x;
	ch[old][w] = ch[x][w^1]; ch[x][w^1] = old;
	fa[ch[old][w]] = old; fa[ch[x][w^1]] = x; fa[x] = oldf;
	upd(old); upd(x);
}
void splay(int x){
	xf(x);
	while(!isRoot(x)){
		int f=fa[x];
		if(!isRoot(f))	rotate(getW(f)==getW(x)?f:x);
		rotate(x);
	}
}
void access(int x){
	int y=0;
	while(x){
		splay(x);
		ch[x][1] = y;
		upd(x);
		y = x;
		x = fa[x];
	}
}
void makeRoot(int x){
	access(x);
	splay(x);
	rev[x] ^= 1;
}
void link(int u, int v){
	makeRoot(u);
	fa[u] = v;
}
void cut(int u, int v){
	makeRoot(u);
	access(v);
	splay(v);
	ch[v][0] = fa[u] = 0;
}
int main(){
	cin>>n;
	for(int i=1; i<=n; i++){
		scanf("%d", &ski[i]);
		if(i+ski[i]>n)	link(i, n+1);
		else	link(i, i+ski[i]);
	}
	cin>>m;
	while(m--){
		scanf("%d", &opt);
		if(opt==1){
			scanf("%d", &uu);
			uu++;
			makeRoot(uu);
			access(n+1);
			splay(n+1);
			printf("%d\n", siz[n+1]-1);
		}
		else{
			scanf("%d %d", &uu, &vv);
			uu++;
			if(uu+ski[uu]>n)	cut(uu, n+1);
			else	cut(uu, uu+ski[uu]);
			ski[uu] = vv;
			if(uu+ski[uu]>n)	link(uu, n+1);
			else	link(uu, uu+ski[uu]);
		}
	}
	return 0;
}