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HDU3487 Play With Chains(Splay)

2024-07-11 08:48:22   223人阅读

很裸的Splay,抄一下CLJ的模板当作复习，debug了一个下午，收获是终于搞懂了以前看这个模板里不懂的内容。以前用这个模板的时候没有看懂为什么get函数返回的前缀要加个引用，经过一下午的debug终于明白，如果加了引用的时候是会被修改到的，删除实际上就是将root->ch[1]->ch[0]置为null，但由于我们还要把这一段插回去，所以get的时候的t前面没有加引用，否则一旦置为null的话 t也会变为null。还有就是这次是第一次用这个模板进行插入，本题倒腾了很久就是在这个插入上，没有找到合适的姿势。经过摸索一个正确的姿势是在  1 2 3 4 5 ... n 的第k个位置后插入，应该是先get(k+1,k+1),然后直接在root->ch[1]里设置左儿子即可。复习Splay是为了学习LCT做准备吧。。－ －0

#pragma warning(disable:4996)#include <iostream>#include <cstring>#include <string>#include <cstdio>#include <vector>#include <algorithm>#include <map>using namespace std;#define ll long long#define maxn 350000struct Node{	Node *ch[2], *p;	int size,val;	int rev;	Node(){ size = 0; val = 0; rev = 0; }	bool d(){		return this == p->ch[1];	}	void setc(Node *c, int d){		ch[d] = c; c->p = this;	}	void relax();	void revIt()	{		rev ^= 1;	}	void upd(){		size = ch[0]->size + ch[1]->size + 1;	}}Tnull,*null=&Tnull;Node mem[maxn], *C = mem;void Node::relax(){	if (rev){		swap(ch[0], ch[1]);		for (int i = 0; i < 2; i++){			if (ch[i] != null) ch[i]->revIt();		}		rev = 0;	}}Node *make(int v){	C->ch[0] = C->ch[1] = null;	C->size = 1; C->val = v; C->rev = 0;	return C++;}Node* build(int l, int r){	if (l >= r) return null;	int m = (l + r) >> 1;	Node *t = make(m);	t->setc(build(l, m), 0);	t->setc(build(m + 1, r), 1);	t->upd();	return t;}Node *root;void rot(Node *t){	Node *p = t->p;	p->relax();	t->relax();	int d = t->d();	p->p->setc(t, p->d());	p->setc(t->ch[!d], d);	t->setc(p, !d);	p->upd();	if (p == root) root = t;}void splay(Node *t, Node *f = null){	while (t->p != f){		if (t->p->p == f) rot(t);		else t->d() == t->p->d() ? (rot(t->p), rot(t)) : (rot(t), rot(t));	}	t->upd();}Node* select(int k) {	for (Node*t = root;;) {		t->relax();		int c = t->ch[0]->size;		if (k == c)			return t;		if (k > c)			k -= c + 1, t = t->ch[1];		else			t = t->ch[0];	}}Node*&get(int l, int r) { //[l,r)	Node*L = select(l - 1);	Node*R = select(r);	splay(L);	splay(R, L);	return R->ch[0];}int n, m;int main(){	while (cin >> n >> m)	{		if (n <0 && m <0) break;		memset(mem, 0, sizeof(mem));		C = mem;		root = build(0, n + 2); root->p = null;		char oper[10];		int li, ri, wi;		for (int i = 0; i < m; i++){			scanf("%s", oper);			if (oper[0] == ‘C‘){				scanf("%d%d%d", &li, &ri, &wi);				Node *t = get(li, ri + 1);				root->ch[1]->ch[0] = null;				splay(root->ch[1]);				Node *&x = get(wi+1, wi+1);				root->ch[1]->setc(t, 0);			}			else{				scanf("%d%d", &li, &ri);				Node *&t = get(li, ri + 1);				t->revIt();				splay(t);			}		}		for (int i = 1; i <= n; i++){			if (i >= 2) printf(" ");			Node *&t = get(i, i + 1);			printf("%d", t->val);		}		puts("");	}	return 0;}

 


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