【动态树】 BZOJ 2002 弹飞绵羊

最新推荐文章于 2020-01-23 13:56:18 发布

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本文介绍了一种使用动态树和虚拟节点解决特定问题的方法。通过动态树进行节点旋转、路径查询等操作，并利用虚拟节点简化了算法实现过程。适用于需要高效处理节点间关系变化的应用场景。

设一个虚拟节点然后用动态树做就可以了。。。

#include <iostream>
#include <queue> 
#include <stack> 
#include <map> 
#include <set> 
#include <bitset> 
#include <cstdio> 
#include <algorithm> 
#include <cstring> 
#include <climits>
#include <cstdlib>
#include <cmath>
#include <time.h>
#define maxn 200005
#define maxm 400005
#define eps 1e-10
#define mod 1000000007
#define INF 0x3f3f3f3f
#define PI (acos(-1.0))
#define lowbit(x) (x&(-x))
#define mp make_pair
#define ls o<<1
#define rs o<<1 | 1
#define lson o<<1, L, mid 
#define rson o<<1 | 1, mid+1, R
#define pii pair<int, int>
//#pragma comment(linker, "/STACK:16777216")
typedef long long LL;
typedef unsigned long long ULL;
//typedef int LL;
using namespace std;
LL qpow(LL a, LL b){LL res=1,base=a;while(b){if(b%2)res=res*base;base=base*base;b/=2;}return res;}
LL powmod(LL a, LL b){LL res=1,base=a;while(b){if(b%2)res=res*base%mod;base=base*base%mod;b/=2;}return res;}
// head

struct node *null;
struct node
{
	int size, rev;
	node *fa, *ch[2];

	inline bool d()
	{
		return fa->ch[1] == this;
	}

	inline bool isroot()
	{
		return fa == null || fa->ch[0] != this && fa->ch[1] != this;
	}

	inline void setc(node *p, int d)
	{
		ch[d] = p;
		p->fa = this;
	}

	inline void pushup()
	{
		size = ch[0]->size + ch[1]->size + 1;
	}

	inline void flip()
	{
		if(this == null) return;
		swap(ch[0], ch[1]);
		rev ^= 1;
	}
	
	inline void pushdown()
	{
		if(rev) {
			ch[0]->flip();
			ch[1]->flip();
			rev = 0;
		}
	}

	inline void go()
	{
		if(!isroot()) fa->go();
		pushdown();
	}

	void rot()
	{
		node *f = fa, *ff = fa->fa;
		int c = d(), cc = fa->d();
		f->setc(ch[!c], c);
		this->setc(f, !c);
		if(ff->ch[cc] == f) ff->setc(this, cc);
		else this->fa = ff;
		f->pushup();
	}

	node* splay()
	{
		go();
		while(!isroot()) {
			if(!fa->isroot()) d() == fa->d() ? fa->rot() : rot();
			rot();
		}
		pushup();
		return this;
	}

	node* access()
	{
		for(node *p = this, *q = null; p != null; q = p, p = p->fa) {
			p->splay()->setc(q, 1);
			p->pushup();
		}
		return splay();
	}

	inline int query()
	{
		return access()->size;
	}

	inline void makeroot()
	{
		access()->flip();
	}

	void cut()
	{
		access();
		ch[0]->fa = null;
		ch[0] = null;
		pushup();
	}

	void link(node *p)
	{
		makeroot();
		fa = p;
	}
};

node pool[maxm];
node *Node[maxn];
node *tail;
int n, m;

void init()
{
	tail = pool;
	null = tail++;
	null->fa = null->ch[0] = null->ch[1] = null;
	null->size = 0;
	for(int i = 1; i <= n; i++) {
		tail->fa = tail->ch[0] = tail->ch[1] = null;
		tail->size = 1;
		Node[i] = tail++;
	}
	tail->fa = tail->ch[0] = tail->ch[1] = null;
	tail->size = 0;
}

void read()
{
	int x;
	for(int i = 1; i <= n; i++) {
		scanf("%d", &x);
		if(i + x > n) Node[i]->fa = tail;
		else Node[i]->fa = Node[i + x];
	}
	scanf("%d", &m);
}

void work()
{
	int k, x;
	while(m--) {
		scanf("%d", &k);
		if(k == 1) {
			scanf("%d", &x), x++;
			printf("%d\n", Node[x]->query() - 1);
		}
		else {
			scanf("%d%d", &k, &x), k++;
			Node[k]->cut();
			if(k + x > n) Node[k]->link(tail);
			else Node[k]->link(Node[k + x]);
		}
	}
}

int main(void)
{
	while(scanf("%d", &n)!=EOF) {
		init();
		read();
		work();
	}

	return 0;
}