[替罪羊树 模板题] BZOJ 3224 Tyvj 1728 普通平衡树

替罪羊树的模板题
关于删除 有人说按照BST的方法删 那样讨论太烦啦
直接打个标记表示已被删 下次重构的时候丢掉就好了

#include<cstdio>#include<cstdlib>#include<algorithm>using namespace std;inline char nc(){  static char buf[100000],*p1=buf,*p2=buf;  if (p1==p2) { p2=(p1=buf)+fread(buf,1,100000,stdin); if (p1==p2) return EOF; }  return *p1++;}inline void read(int &x){  char c=nc(),b=1;  for (;!(c>='0' && c<='9');c=nc()) if (c=='-') b=-1;  for (x=0;c>='0' && c<='9';x=x*10+c-'0',c=nc()); x*=b;}const int N=200005;#define ab 0.75struct node{  node *ch[2];  int key,size,cover,ext;  void update() { size=ch[0]->size+ch[1]->size+ext,cover=ch[0]->cover+ch[1]->cover+1; }  bool bad() { return ch[0]->cover>=cover*ab+5 || ch[1]->cover>=cover*ab+5; }}Mem[N],*null,*root;node *Stack[N]; int pnt;node *lst[N]; int len;inline void Init(){  root=null=Mem; null->size=null->cover=0; null->ch[0]=null->ch[1]=null;  for (int i=1;i<N;i++) Stack[++pnt]=Mem+i;}inline node *New(int key){  node *t=Stack[pnt--];  t->ch[0]=t->ch[1]=null; t->size=t->cover=t->ext=1; t->key=key;  return t;}inline void travel(node *p){  if (p==null) return;  travel(p->ch[0]); if (p->ext) lst[++len]=p; else Stack[++pnt]=p; travel(p->ch[1]);}inline node *divide(int l,int r){  if (l>r) return null;  int mid=(l+r)>>1;  lst[mid]->ch[0]=divide(l,mid-1); lst[mid]->ch[1]=divide(mid+1,r); lst[mid]->update();  return lst[mid];}inline void rebuild(node *&p){  len=0; travel(p); p=divide(1,len);}inline node **insert(node *&p,int key){  if (p==null){ p=New(key); return &null; }  p->size++; p->cover++;  node **ret=insert(p->ch[key>=p->key],key);  if (p->bad()) ret=&p;  return ret;}inline void erase(node *p,int k){  p->size--;  if (p->ext && k==p->ch[0]->size+1) return void(p->ext=0);  if (k<=p->ch[0]->size) erase(p->ch[0],k); else erase(p->ch[1],k-p->ch[0]->size-p->ext);}inline int Kth(int k){  node *p=root;  while (p!=null){    if (p->ext && k==p->ch[0]->size+1) return p->key;    else if (p->ch[0]->size>=k) p=p->ch[0];    else k-=p->ch[0]->size+p->ext,p=p->ch[1];  }}inline int Rank(int val){  node *p=root; int ret=1;  while (p!=null)    if (p->key>=val)      p=p->ch[0];    else      ret+=p->ch[0]->size+p->ext,p=p->ch[1];  return ret;}inline void Insert(int val){  node **p=insert(root,val);  if (*p!=null) rebuild(*p);}void Erase_kth(int k){  erase(root,k);  if (root->size<ab*root->cover) rebuild(root);}void Erase(int k){  Erase_kth(Rank(k));}int main(){  int Q,order,x;  freopen("t.in","r",stdin);  freopen("t.out","w",stdout);  Init();  read(Q);  while (Q--){    read(order),read(x);    if (order==1) Insert(x);    else if (order==2) Erase(x);    else if (order==3) printf("%d\n",Rank(x));    else if (order==4) printf("%d\n",Kth(x));    else if (order==5) printf("%d\n",Kth(Rank(x)-1));    else if (order==6) printf("%d\n",Kth(Rank(x+1)));  }  return 0;}