【模板】Splay

bzoj 3223

#include<bits/stdc++.h>using namespace std;struct Node{    Node *ch[2],*fa;    int key,siz;    bool flip;    Node(int);    int dir(int val){        if(val==ch[0]->siz+1)   return -1;        return val>ch[0]->siz+1;    }    int son(){        if(fa->ch[0]==this)     return 0;        if(fa->ch[1]==this)     return 1;        return -1;    }    void maintain(){siz=ch[0]->siz+ch[1]->siz+1;}    void pushdown(){        if(flip){            swap(ch[0],ch[1]);            ch[0]->flip^=1;ch[1]->flip^=1;            flip=false;        }    }}*null,*root;Node::Node(int _=-1){    key=_;    siz=null?1:0;    flip=false;    ch[0]=ch[1]=fa=null;}void buildtree(Node* &o,int l,int r){    if(l>r) {o=null;return;}    int mid=l+r>>1;    o=new Node(mid);    buildtree(o->ch[0],l,mid-1);o->ch[0]->fa=o;    buildtree(o->ch[1],mid+1,r);o->ch[1]->fa=o;    o->maintain();}void Rotate(Node *o,int dir){    Node *tmp=o->ch[dir^1];    o->ch[dir^1]=tmp->ch[dir];    tmp->ch[dir]->fa=o;    tmp->ch[dir]=o;    o->maintain();  tmp->maintain();    if(~o->son())  o->fa->ch[o->son()]=tmp;    tmp->fa=o->fa;  o->fa=tmp;}void print(Node *o){    if(o==null)     return;    o->pushdown();    print(o->ch[0]);    printf("%d ",o->key);    print(o->ch[1]);}void Pushdown(Node *o){    if(o->fa!=null) Pushdown(o->fa);    o->pushdown();}void Splay(Node *o){    while(~o->son()){        int dir=o->son();        if(dir==o->fa->son())   Rotate(o->fa->fa,dir^1);        Rotate(o->fa,dir^1);    }}Node *Kth(Node *o,int k){    o->pushdown();    int dir=o->dir(k);    if(dir==1)  k-=o->ch[0]->siz+1;    if(dir==-1) return o;    else        return Kth(o->ch[dir],k);}Node *Merge(Node *lhs,Node *rhs){    if(lhs==null)   return rhs;    if(rhs==null)   return lhs;    Node *tmp=Kth(lhs,lhs->siz);    Splay(tmp);    tmp->ch[1]=rhs;    rhs->fa=tmp;    tmp->maintain();    return tmp;}void Split(Node *org,int k,Node* &lhs,Node* &rhs){    if(k==0){        lhs=null;rhs=org;        return;    }    else if(k==org->siz){        lhs=org;rhs=null;        return;    }    Node* tmp=Kth(org,k);    Splay(tmp);    lhs=tmp;rhs=tmp->ch[1];    rhs->fa=null;lhs->ch[1]=null;lhs->maintain();}void Reverse(int l,int r){    Node *lhs,*tmp,*mid,*rhs;    Split(root,l-1,lhs,mid);    Split(mid,r-l+1,mid,rhs);    mid->flip^=1;    root=Merge(Merge(lhs,mid),rhs);}int main(){    null=new Node();    null->ch[0]=null->ch[1]=null->fa=null;    root=null;    int n,m;    scanf("%d%d",&n,&m);    buildtree(root,1,n);    for(int i=1;i<=m;++i){        int l,r;        scanf("%d%d",&l,&r);        Reverse(l,r);    }    print(root);    return 0;}

借鉴自BulaBulaCHN学长