HDU3487 Play With Chains(Splay)

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 350000

struct 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;
}