Input Specification:

Each input file contains one test case. For each case, the first line contains a positive integerN(≤) which is the total number of keys to be inserted. ThenNdistinct integer keys are given in the next line. All the numbers in a line are separated by a space.

Output Specification:

For each test case, print the root of the resulting AVL tree in one line.

#include <bits/stdc++.h>
using namespace std;
int n;
struct node{
    int v,height;
    node *lchild,*rchild;
} *root;

node* newNode(int v){
    node *Node = new node;//申請一個新的地址空間 
    Node->v = v;
    Node->height = 1
 
;
    Node->lchild = Node->rchild = NULL;
    return Node; 
}

//返回以root為根節點的子樹當前的height 
int getHeight(node *root){
    if(root == NULL) return 0;
    return root->height;
}

//更新節點root的heifht 

//由於在涉及到相應的AVL樹進行相應的調整時，只有部分節點的高度發生了相應的變化，所以在進行調整時
//直接呼叫每個節點對應的height進行相應的更新，而不需要遞迴進行更新 
void updateHeight(node* root){
    
 
//left和right中max進行相應的更新 
    root->height = max(getHeight(root->lchild),getHeight(root->rchild))+1;
} 
int getBalanceFactor(node* root){
    return getHeight(root->lchild)-getHeight(root->rchild);
}

//對AVL樹調整的兩個關鍵操作
void L(node* &root){
    node* temp = root->rchild;
    root->rchild = temp->lchild;
    temp->lchild = root;
    updateHeight(root);//注意需要從下面的節點進行相應的更新
    updateHeight(temp);
    root = temp; 
}

//右旋
void R(node* &root){
    node* temp =  root->lchild;
    root->lchild = temp->rchild;
    temp->rchild = root;
    updateHeight(root);
    updateHeight(temp);
    root = temp;
} 
 
void insert(node *&root,int v){
    //進行插入
    if(root == NULL){
        root = newNode(v);
        return;
    } 
    if(v < root->v){
        //由於插入的是左子樹，所以只能導致L形開頭 
        insert(root->lchild,v);
        updateHeight(root);//實際上這個高度的更新是一個遞迴的更新 
        if(getBalanceFactor(root) ==2){
            //需要進行相應的調整
            if(getBalanceFactor(root->lchild) == 1){
                //ll形，直接對根進行相應的右旋就行
                R(root); 
            }else if(getBalanceFactor(root->lchild) == -1){
                //LR形，先對左子樹左旋，然後再右旋 
                 L(root->lchild);
                 R(root); 
            }
        } 
    }    
    else{
        insert(root->rchild,v);
        updateHeight(root);
        if(getBalanceFactor(root) == -2){
            //需要進行相應的調整
            if(getBalanceFactor(root->rchild) == -1){
                //RR形
                L(root);//直接進行左旋即可 
            }
            else if(getBalanceFactor(root->rchild) == 1){
                //RL形
                R(root->rchild);
                L(root);
            }
        }
    } 
}
int main(){
    int n;
    cin>>n;
    int tmp;
    node* root = NULL;
    for(int i=0;i<n;i++){
        cin>>tmp;
        insert(root,tmp);
    }
    cout<<root->v<<endl;
    return 0;
}