[Template] general balanced tree

emm two days to finally learn the balance of the tree, he did not board, the board can only rely on the Internet to learn the big brother, big brother feel very good playing board.

Original: https: //blog.csdn.net/a_comme_amour/article/details/79382104

Los evaluation Valley: https: //www.luogu.org/record/22239881

  1 #include<bits/stdc++.h>
  2 using namespace std;
  3 const int N=1e5+8;
  4 int ch[N][2],f[N],siz[N],cnt[N],val[N];
  5 int sz,rt;
  6 inline void clear(int x){
  7     ch[x][0]=ch[x][1]=f[x]=siz[x]=cnt[x]=val[x]=0;
  8 }
  9 inline bool get(int x){
 10     return ch[f[x]][1]==x;
 11 }
 12 inline void update(int x){
 13     if(x){
 14         siz[x]=cnt[x];
 15         if(ch[x][0]) siz[x]+=siz[ch[x][0]];
 16         if(ch[x][1]) siz[x]+=siz[ch[x][1]];
 17     }
 18 }
 19 inline void rotate(int x){
 20     int fa=f[x],ffa=f[fa],which=get(x);
 21     ch[fa][which]=ch[x][which^1];f[ch[fa][which]]=fa;
 22     ch[x][which^1]=fa;f[fa]=x;
 23     f[x]=ffa;
 24     if(ffa) ch[ffa][ch[ffa][1]==fa]=x;
 25     update(fa);update(x);
 26 }
 27 inline void splay(int x){
 28     for(int fa;fa=f[x];rotate(x)){
 29         if(f[fa]){
 30             rotate( (get(x)==get(fa)) ? fa : x );
 31         }
 32     }
 33     rt=x;
 34 }
 35 inline void ins(int x){
 36     if(!rt){
 37         ++sz;ch[sz][0]=ch[sz][1]=f[sz]=0;
 38         rt=sz;siz[sz]=cnt[sz]=1;val[sz]=x;
 39         return;
 40     }
 41     int now=rt,fa=0;
 42     while(1){
 43         if(x==val[now]){
 44             ++cnt[now];
 45             update(now);update(fa);
 46             splay(now);
 47             return;
 48         }
 49         fa=now;
 50         now=ch[now][val[now]<x];
 51         if(!now){
 52             ++sz;
 53             ch[sz][0]=ch[sz][1]=0;
 54             f[sz]=fa;
 55             siz[sz]=cnt[sz]=1;
 56             ch[fa][val[fa]<x]=sz;
 57             val[sz]=x;
 58             update(fa);
 59             splay(sz);
 60             return;
 61         }
 62     }
 63 }
 64 inline int rnk(int x){
 65     int now=rt,ans=0;
 66     while(1){
 67         if(x<val[now]) now=ch[now][0];
 68         else{
 69             ans+=(ch[now][0]?siz[ch[now][0]]:0);
 70             if(x==val[now]){
 71                 splay(now);
 72                 return ans+1;
 73             }
 74             ans+=cnt[now];
 75             now=ch[now][1];
 76         }
 77     }
 78 }
 79 inline int kth(int x){
 80     int now=rt;
 81     while(1){
 82         if(ch[now][0] && x<=siz[ch[now][0]]) now=ch[now][0];
 83         else{
 84             int tem=(ch[now][0]?siz[ch[now][0]]:0)+cnt[now];
 85             if(x<=tem) return val[now];
 86             x-=tem;now=ch[now][1];
 87         }
 88     }
 89 }
 90 inline int pre(){
 91     int now=ch[rt][0];
 92     while(ch[now][1]) now=ch[now][1];
 93     return now;
 94 }
 95 inline int nex(){
 96     int now=ch[rt][1];
 97     while(ch[now][0]) now=ch[now][0];
 98     return now;
 99 }
100 inline void del(int x){
101     rnk(x);
102     if(cnt[rt]>1){--cnt[rt]; update(rt); return;}
103     if(!ch[rt][0] && !ch[rt][1]) {clear(rt); rt=0; return;}
104     if(!ch[rt][0]){
105         int oldrt=rt; rt=ch[rt][1]; f[rt]=0;
106         clear(oldrt); return;
107     }
108     if(!ch[rt][1]){
109         int oldrt=rt; rt=ch[rt][0]; f[rt]=0;
110         clear(oldrt); return;
111     }
112     int lebig=pre(),oldrt=rt;
113     splay(lebig);
114     ch[rt][1]=ch[oldrt][1];
115     f[ch[oldrt][1]]=rt;
116     clear(oldrt);
117     update(rt);
118 }
119 int main(){
120     int n;scanf("%d",&n);
121     for(int i=1;i<=n;++i){
122         int op,x;scanf("%d %d",&op,&x);
123         switch(op){
124             case 1:ins(x);break;
125             case 2:del(x);break;
126             case 3:printf("%d\n",rnk(x));break;
127             case 4:printf("%d\n",kth(x));break;
128             case 5:ins(x);printf("%d\n",val[pre()]);del(x);break;
129             case 6:ins(x);printf("%d\n",val[nex()]);del(x);break;
130         }
131     }
132     return 0;
133 }

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