# bzoj 3224（平衡树）

## 代码：

#include <bits/stdc++.h>
using namespace std;
const int maxn=200005;

int ch[maxn][2],par[maxn],val[maxn],cnt[maxn],size[maxn],ncnt,root;
bool chk(int x){
return ch[par[x]][1]==x;
}
void push_up(int x){
size[x]=size[ch[x][0]]+size[ch[x][1]]+cnt[x];
}
void rotate(int x){
int y=par[x],z=par[y],k=chk(x),w=ch[x][k^1];
ch[y][k]=w; par[w]=y;
ch[z][chk(y)]=x;par[x]=z;
ch[x][k^1]=y; par[y]=x;
push_up(y);
push_up(x);
}

void splay(int x,int goal=0){
while(par[x]!=goal){
int y=par[x],z=par[y];
if(z!=goal){
if(chk(x)==chk(y)) rotate(y);
else rotate(x);

}
rotate(x);
}
if(!goal) root=x;
}

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

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

int kth(int k){
int cur=root;
while(1){
if(ch[cur][0]&&k<=size[ch[cur][0]]){
cur=ch[cur][0];
}else if(k>size[ch[cur][0]]+cnt[cur]){
k-=size[ch[cur][0]]+cnt[cur];
cur=ch[cur][1];
}else return cur;
}
}
int pre(int x){
find(x);
if(val[root]<x) return root;
int cur=ch[root][0];
while(ch[cur][1]) cur=ch[cur][1];
return cur;
}

int succ(int x){
find(x);
if(val[root]>x) return root;
int cur=ch[root][1];
while(ch[cur][0]) cur=ch[cur][0];
return cur;
}

void remove(int x){
int last=pre(x),next=succ(x);
splay(last);
splay(next,last);
int del=ch[next][0];
if(cnt[del]>1){
cnt[del]--;
splay(del);
}
else ch[next][0]=0,push_up(next),push_up(root);
}
int n,op,x;

int main()
{
scanf("%d",&n);
insert(0x3f3f3f3f);
insert(0xcfcfcfcf);
while(n--){
scanf("%d%d",&op,&x);
if(op==1) insert(x);
if(op==2) remove(x);
if(op==3){
find(x);
printf("%d\n",size[ch[root][0]]);
}
if(op==4){
printf("%d\n",val[kth(x+1)]);
}
if(op==5){
printf("%d\n",val[pre(x)]);
}
if(op==6){
printf("%d\n",val[succ(x)]);
}
}
}


posted @ 2019-03-21 22:37  ChenJr  阅读(145)  评论(0编辑  收藏  举报