Codeforces 675D Tree Construction Splay伸展树

#include <bits/stdc++.h>
#define endl ‘\n‘
#define ll long long
#define IO ios::sync_with_stdio(false)
using namespace std;
const int maxn=1e6+10,maxm=2e6+10;
const int INF=0x3f3f3f3f;
const int mod=1e9+7;
const double PI=acos(-1.0);
//head
int casn,n,m,k;
int num[maxn];
class splaytree{
  public:
  struct splaynode{
    splaynode *son[2],*pre;
    ll val;
    splaynode(int x=0,splaynode *fa=NULL){
      pre=fa;
			son[0]=son[1]=NULL;
    	val=x;
    }
  };
  typedef struct splaynode* nodep;
  int cnt;
  nodep root;
  vector<splaynode> node;
	void rotate(nodep now,int d){
    nodep fa=now->pre;
    fa->son[!d]=now->son[d];
    if(now->son[d]) now->son[d]->pre=fa;
    now->pre=fa->pre;
    if(fa->pre){
      if(fa->pre->son[0]==fa) fa->pre->son[0]=now;
      else fa->pre->son[1]=now;
    }else root=now;
    now->son[d]=fa;
    fa->pre=now;
  }
  void splay(nodep now,nodep dst){
    while(now->pre!=dst){
      if(now->pre->pre==dst)rotate(now,now->pre->son[0]==now);
      else{
	    	nodep fa=now->pre;
	    	int d=(fa->pre->son[0]==fa);
		    if(fa->son[d]==now){
		    	rotate(now,!d);
					rotate(now,d);
				}else {
					rotate(fa,d);
					rotate(now,d);
				}
			}
    }
    if(!dst) root=now;
  }
  int insert(int val){
		if(!root) {
			node[cnt]=splaynode(val);
			root=&node[cnt++];
			return 1;
		}
		nodep now=root;
		int flag=(now->val)<val;
		while(now->son[flag]){
			if((now->val)==val){
				splay(now,NULL);
				return 0;
			}
			now=now->son[flag];
			flag=((now->val)<val);
		}
		node[cnt]=splaynode(val,now);
		now->son[flag]=&node[cnt++];
		splay(now->son[flag],NULL);
		return 1;
  }
  int bound(int d){
		nodep now=root->son[d];
		if(!now) return INF;
		while(now->son[d^1]) now=now->son[d^1];
		return now->val;
  }
  splaytree(int n){
    cnt=0;
    node.resize(n+7);
    root=NULL;
  }
};
map<int,int> vis;
int main() {
	IO;
	cin>>n;
	splaytree tree(n);
	while(n--){
		int a;
		cin>>a;
		vis[a]=maxn-n;
		if(tree.root==NULL){
			tree.insert(a);
			continue;
		}
		if(tree.insert(a)==0) continue;
		int mn=tree.bound(0);
		int mx=tree.bound(1);
		if(vis[mn]>vis[mx]) cout<<mn<<‘ ‘;
		else cout<<mx<<‘ ‘;
	}
	return 0;
}