1066. Root of AVL Tree

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#include<algorithm>#include<iostream>using namespace std;struct node{    node*lch,*rch;    int key;    node(int x):key(x){lch=rch=nullptr;}};using ptr=node*;int deep(ptr p){    if(!p)return 0;    return max(deep(p->lch),deep(p->rch))+1;}ptr ll(ptr p){//右旋    ptr l=p->lch;    p->lch=l->rch,l->rch=p;    return l;}ptr rr(ptr p){//左旋    ptr r=p->rch;    p->rch=r->lch,r->lch=p;    return r;}ptr rl(ptr p){    p->rch=ll(p->rch);    return rr(p);}ptr lr(ptr p){    p->lch=rr(p->lch);    return ll(p);}ptr insert(ptr p,int x){    if(!p)return new node(x);    if(x<p->key)    {        p->lch=insert(p->lch,x);        if(deep(p->lch)-deep(p->rch)==2)            return x<p->lch->key?ll(p):lr(p);    }else    {        p->rch=insert(p->rch,x);        if(deep(p->rch)-deep(p->lch)==2)            return x<p->rch->key?rl(p):rr(p);    }    return p;}int main(){    int n;cin>>n;    ptr p=nullptr;    for(int t,i=0;i<n;++i)    {        cin>>t;        p=insert(p,t);    }    cout<<p->key;}

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