【Splay】bzoj3224 Tyvj 1728 普通平衡树

#include<cstdio>
#include<iostream>
#include<cstring>
#include<algorithm>
using namespace std;
#define maxn 1000000
#define INF 2147483647
int n,fa[maxn],val[maxn],c[maxn][2],root,tot,siz[maxn],cnt[maxn];
void Maintain(int x)
{
    siz[x]=siz[c[x][0]]+siz[c[x][1]]+cnt[x];
}
void NewNode(int &x,int Fa,int key)
{
    x=++tot;
    fa[x]=Fa;
    c[x][0]=c[x][1]=0;
    val[x]=key;
    siz[x]=cnt[x]=1;
}
void Rotate(int x,bool flag)
{
    int y=fa[x];
    c[y][!flag]=c[x][flag];
    fa[c[x][flag]]=y;
    if(fa[y]){
        c[fa[y]][c[fa[y]][1]==y]=x;
    }
    fa[x]=fa[y];
    c[x][flag]=y;
    fa[y]=x;
    Maintain(y);
}
void Splay(int x,int goal)
{
    if(!x){
        return;
    }
    int y;
    while((y=fa[x])!=goal){
        if(fa[y]==goal){
            Rotate(x,c[y][0]==x);
        }
        else{
            if((c[y][0]==x)==(c[fa[y]][0]==y)){
                Rotate(y,c[fa[y]][0]==y);
            }
            else{
                Rotate(x,c[y][0]==x);
                y=fa[x];
            }
            Rotate(x,c[y][0]==x);
        }
    }
    Maintain(x);
    if(!goal){
        root=x;
    }
}
int Find(int key,int x=root)
{
    while(c[x][val[x]<key]){
        if(val[x]==key){
            return x;
        }
        x=c[x][val[x]<key];
    }
    return x;
}
void Insert(int key)
{
    if(!root){
        NewNode(root,0,key);
        return;
    }
    int x=Find(key);
    if(val[x]==key){
        ++cnt[x];
        Splay(x,0);
        return;
    }
    NewNode(c[x][val[x]<key],x,key);
    Splay(c[x][val[x]<key],0);
}
int Findmax(int x=root)
{
    while(c[x][1]){
        x=c[x][1];
    }
    return x;
}
int Findmin(int x=root)
{
    while(c[x][0]){
        x=c[x][0];
    }
    return x;
}
void Delete(int key)
{
    int x=Find(key);
    Splay(x,0);
    if(val[x]==key){
        --cnt[x];
        if(!cnt[x]){
            if(!c[x][0]&&!c[x][1]){
                root=0;
            }
            else if(!c[x][0]||!c[x][1]){
                fa[c[x][c[x][0]==0]]=0;
                root=c[x][c[x][0]==0];
            }
            else{
                int y=Findmax(c[x][0]);
                Splay(y,root);
                c[y][1]=c[root][1];
                fa[c[root][1]]=y;
                root=y;
                fa[root]=0;
                Maintain(root);
            }
        }
        else{
            Maintain(x);
        }
    }
}
int Rank(int key)
{
    int x=Find(key);
    Splay(x,0);
    return siz[c[x][0]]+1;
}
int Kth(int K,int x=root)
{
    while(1){
        int Siz0=siz[c[x][0]];
        if(K<=Siz0){
            x=c[x][0];
        }
        else if(K<=Siz0+cnt[x]){
            return val[x];
        }
        else{
            K-=(Siz0+cnt[x]);
            x=c[x][1];
        }
    }
}
int GetPre(int key)
{
    int x=Find(key);
    if(val[x]==key){
        Splay(x,0);
        return val[Findmax(c[x][0])];
    }
    while(val[x]>key&&fa[x]){
        x=fa[x];
    }
    return val[x];
}
int GetNex(int key)
{
    int x=Find(key);
    if(val[x]==key){
        Splay(x,0);
        return val[Findmin(c[x][1])];
    }
    while(val[x]<key&&fa[x]){
        x=fa[x];
    }
    return val[x];
}
int main(){
    int op, x;
    scanf("%d",&n);
    for(int i=1;i<=n;i++){
        scanf("%d%d",&op,&x);
        if(op==1){
            Insert(x);
        }
        else if(op==2){
            Delete(x);
        }
        else if(op==3){
            printf("%d\n",Rank(x));
        }
        else if(op==4){
            printf("%d\n",Kth(x));
        }
        else if(op==5){
            printf("%d\n",GetPre(x));
        }
        else{
            printf("%d\n",GetNex(x));
        }
    }
    return 0;
}