Luo Gu [P3835] [template] can persist balanced tree

Be persistent non-rotating treap, really good writing and good tune ~ 

code: 

#include <cstdio>  
#include <cstdlib>
#include <algorithm> 
#define N 500007 
#define lson t[x].ls 
#define rson t[x].rs 
#define inf 2147483647   
#define setIO(s) freopen(s".in","r",stdin)     
using namespace std;   
int tot;
int cur; 
int Pr; 
int Nx;     
int rt[N];   
struct node {   
    int val; 
    int size; 
    int ls,rs; 
    int ran;   
}t[N*50];              
int newnode() { 
    ++tot;   
    t[tot].val=0; 
    t[tot].size=1; 
    t[tot].ran=rand(); 
    t[tot].ls=t[tot].rs=0;   
    return tot;  
}        
void pushup(int x) { 
    t[x].size=t[lson].size+t[rson].size+1;   
}
void split(int x,int v,int &l,int &r) {
    if(!x) {
        l=r=0; 
    } 
    else {  
        int now=newnode();  
        t[now]=t[x];              
        if(t[x].val<=v) {                   
            l=now;  
            split(rson,v,t[l].rs,r); 
        }
        else {
            r=now;  
            split(lson,v,l,t[r].ls);   
        }   
        pushup(now); 
    }
}
int merge(int x,int y) {
    if(!x||!y) {
        return x+y;   
    }       
    int now=newnode();    
    if(t[x].ran<t[y].ran) {        
        t[now]=t[x]; 
        t[now].rs=merge(t[x].rs,y);  
    }
    else {    
        t[now]=t[y];  
        t[now].ls=merge(x,t[y].ls);  
    }
    pushup(now);     
    return now;  
}       
void Insert(int val) {   
    int x=0; 
    int y=0;             
    split(rt[cur],val,x,y);   
    int _new=newnode();   
    t[_new].val=val;        
    _new=merge(x,_new);     
    y=merge(_new,y);          
    rt[cur]=y;  
}
void Delete(int val) {
    int x=0; 
    int y=0; 
    int z=0;   
    split(rt[cur],val,x,z);    
    split(x,val-1,x,y);                   
    if(y) {       
        y=merge(t[y].ls,t[y].rs);                   
    }      
    y=merge(x,y);   
    z=merge(y,z);   
    rt[cur]=z; 
}
int Rank(int val) {   
    int x=0; 
    int y=0;    
    split(rt[cur],val-1,x,y);     
    int re=t[x].size+1;      
    rt[cur]=merge(x,y);   
    return re;  
}
void Pre(int x,int val) {                   
    if(!x) {
        return;  
    }    
    if(t[x].val<val) {
        Pr=max(Pr,t[x].val);                 
        Pre(rson,val); 
    }  
    else {
        Pre(lson,val);  
    }
}
void Nxt(int x,int val) {   
    if(!x) {
        return; 
    }
    if(t[x].val>val) {
        Nx=min(Nx,t[x].val);  
        Nxt(lson,val); 
    }
    else {
        Nxt(rson,val);   
    }
} 
// 查询排名为 x 的数  
int Num(int x,int kth) { 
    if(t[lson].size+1==kth) {
        return t[x].val; 
    }     
    if(kth<=t[lson].size) {
        return Num(lson,kth); 
    }
    else {
        return Num(rson,kth-t[lson].size-1);   
    }
}
int main() { 
    // setIO("input");  
    int i,j,m; 
    scanf("%d",&m);  
    for(cur=1;cur<=m;++cur) {         
        int v,opt,x;      
        scanf("%d%d%d",&v,&opt,&x);  
        rt[cur]=rt[v];          
        if(opt==1) {
            Insert(x); 
        } 
        if(opt==2) {
            Delete(x); 
        } 
        if(opt==3) {
            printf("%d\n",Rank(x)); 
        }  
        if(opt==4) {
            printf("%d\n",Num(rt[cur],x));  
        }
        if(opt==5) {   
            Pr=-inf;     
            Pre(rt[cur],x);   
            printf("%d\n",Pr); 
        } 
        if(opt==6) {
            Nx=inf;   
            Nxt(rt[cur],x);   
            printf("%d\n",Nx);   
        }
    }
    return 0; 
}