Luogu P3369 [template] general balanced tree

solution

Is the most common splay friends, directly put the code QAQ

Code

#include<iostream>
#include<algorithm>
#include<cstring>
#include<cstdio>
#include<cmath>
#define INF 0x3f3f3f3f
using namespace std;
typedef long long LL;
const int N=1e5+5;

int read()
{
    int x=0,p=1; char ch=getchar();
    while((ch<'0'||ch>'9')&&ch!='-') ch=getchar();
    if(ch=='-') p=-1,ch=getchar();
    while(ch>='0'&&ch<='9') x=(x<<3)+(x<<1)+ch-'0',ch=getchar();
    return x*p;
}

int ch[N][2],par[N],val[N],cnt[N],siz[N],tot,root;

int chk(int x) { return ch[par[x]][1]==x; }

void pushup(int x) { siz[x]=siz[ch[x][0]]+siz[ch[x][1]]+cnt[x]; }

int rotate(int x)
{
    int y=par[x],z=par[y],k=chk(x),w=ch[x][k^1];
    ch[z][chk(y)]=x,par[x]=z;
    ch[y][k]=w,par[w]=y;
    ch[x][k^1]=y,par[y]=x;
    pushup(y),pushup(x);
}

void splay(int x,int goal)
{
    int y,z;
    while(par[x]!=goal)
    {
        y=par[x],z=par[y];
        if(z!=goal)
            chk(x)==chk(y) ? rotate(y):rotate(x);
        rotate(x);
    }
    if(!goal) root=x;
}

void find(int x)
{
    int u=root;
    while(ch[u][x>val[u]] && x!=val[u]) 
        u=ch[u][x>val[u]];
    splay(u,0);
}

void insert(int x)
{
    int u=root,p=0;
    while(u && val[u]!=x) p=u,u=ch[u][x>val[u]];
    if(u) cnt[u]++;
    else 
    {
        u=++tot;
        if(p) ch[p][x>val[p]]=u;
        ch[u][0]=ch[u][1]=0;
        par[u]=p; val[u]=x;
        cnt[u]=siz[u]=1;
    }
    splay(u,0);
}

int kth(int k)
{
    int u=root;
    if(k>siz[u]) return 0;
    for(; ;)
    {
        if(ch[u][0] && k<=siz[ch[u][0]])
            u=ch[u][0];
        else if(k>siz[ch[u][0]]+cnt[u])
            k-=siz[ch[u][0]]+cnt[u],u=ch[u][1];
             else 
                return u;
    }
}
    
int Next(int x,int f)
{
    find(x);
    int u=root;
    if(val[u]>x && f) return u;
    if(val[u]<x && !f) return u;
    u=ch[u][f];
    while(ch[u][f^1]) u=ch[u][f^1];
    return u;
}

void remove(int x)
{
    int last=Next(x,0),next=Next(x,1);
    splay(last,0),splay(next,last);
    int del=ch[next][0];
    if(cnt[del]>1)
        cnt[del]--,splay(del,0);
    else 
        ch[next][0]=0,pushup(next),pushup(root);
}

int main()      
{
    int n,op,x; 
    n=read();
    insert(INF);
    insert(-INF);
    while(n--)
    {
        op=read(),x=read();
        switch (op)
        {
            case 1: insert(x); break ;
            case 2: remove(x); break ;
            case 3: find(x); printf("%d\n",siz[ch[root][0]]); break ;
            case 4: printf("%d\n",val[kth(x+1)]); break ;
            case 5: printf("%d\n",val[Next(x,0)]); break ;
            case 6: printf("%d\n",val[Next(x,1)]); break ;
        }
    }
    return 0;
}