【模板】基于旋转的Treap

#include<cstdio>
#include<algorithm>
using namespace std;
const int maxn=100005,INF=0x3f3f3f3f;
int q;
struct node{
node* s[2];
int k,f,size,cnt;
void maintain() {size=s[0]->size+s[1]->size+cnt;}
};
typedef node* P_node;
struct treap{
node tree[maxn],nil;
P_node null,len,root;
treap(){
root=null=&nil;
null->s[0]=null->s[1]=null;
null->size=null->cnt=0;
len=tree;
}
P_node newnode(int key){
len->k=key;len->f=rand();
len->s[0]=len->s[1]=null;
len->size=len->cnt=1;
return len++;
}
void rot(P_node &x,int d){
P_node k=x->s[d^1];x->s[d^1]=k->s[d];k->s[d]=x;
x->maintain();k->maintain();x=k;
}
void insert(P_node &x,int key){
if (x==null) x=newnode(key);else
if (x->k==key) x->cnt++;else{
int d=key>x->k;
insert(x->s[d],key);if (x->s[d]->f > x->f) rot(x,d^1);
}
x->maintain();
}
void erase(P_node &x,int key){
if (x->k==key){
if (x->cnt>1) x->cnt--;else
if (x->s[0]==null) x=x->s[1];else
if (x->s[1]==null) x=x->s[0];else{
int d=x->s[0]->f < x->s[1]->f;
rot(x,d^1);erase(x->s[d^1],key);
}
}else erase(x->s[key>x->k],key);
x->maintain();
}
int kth(P_node &x,int k){
if (x==null||k<1||k>x->size) return 0;
if (k<=x->s[0]->size) return kth(x->s[0],k);else
if (k>x->s[0]->size+x->cnt) return kth(x->s[1],k-x->s[0]->size-x->cnt);
return x->k;
}
int rank(P_node &x,int key){
if (x->k==key) return x->s[0]->size+1;
if (key<x->k) return rank(x->s[0],key);
return rank(x->s[1],key)+x->s[0]->size+x->cnt;
}
int pred(P_node &x,int key){
if (x==null) return -INF;
if (key<=x->k) return pred(x->s[0],key);
return max(x->k,pred(x->s[1],key));
}
int succ(P_node &x,int key){
if (x==null) return INF;
if (key>=x->k) return succ(x->s[1],key);
return min(x->k,succ(x->s[0],key));
}
void print(P_node &x){
if (x==null) return;
print(x->s[0]);
for (int i=1;i<=x->cnt;i++) printf("%d ",x->k);
print(x->s[1]);
}
void Insert(int x) {insert(root,x);}
void Erase(int x) {erase(root,x);}
int Rank(int x) {return rank(root,x);}
int Kth(int x) {return kth(root,x);}
int Pred(int x) {return pred(root,x);}
int Succ(int x) {return succ(root,x);}
void Print() {print(root);printf("**\n");}
}T;
inline int red(){
int tot=0,f=1;char ch=getchar();
while (ch<'0'||'9'<ch) {if (ch=='-') f=-f;ch=getchar();}
while ('0'<=ch&&ch<='9') tot=tot*10+ch-48,ch=getchar();
return tot*f;
}
int main(){
q=red();
while (q--){
int c=red(),x=red();
if (c==1) T.Insert(x);else
if (c==2) T.Erase(x);else
if (c==3) printf("%d\n",T.Rank(x));else
if (c==4) printf("%d\n",T.Kth(x));else
if (c==5) printf("%d\n",T.Pred(x));else
if (c==6) printf("%d\n",T.Succ(x));
}
return 0;
}