PTA Root of AVL Tree

最新推荐文章于 2023-04-15 00:02:09 发布

drawAgirl

最新推荐文章于 2023-04-15 00:02:09 发布

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本文介绍了AVL树的基本操作，包括插入、删除和平衡调整等关键步骤，深入理解其保持平衡的特性。

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就是基础的avl操作


#include <cstdio>
#include <iostream>
#include <cmath>
#include <algorithm>
#include <vector>
#include <queue>

using namespace std;

typedef struct node {
    int val;
    int height;
    struct node *left;
    struct node *right;
}Node,*TreeNode;


TreeNode newnode(int val){
    TreeNode node = new Node;
    node->val = val;
    node->height = 1;
    node->left = node->right = NULL;
    return node;
}

int getHeight(TreeNode root){
    if(!root) return 0;
    return root->height;
}

int getBalance(TreeNode root){
    return getHeight(root->left) - getHeight(root->right);
}

void updateHeight(TreeNode root){
    root->height = max(getHeight(root->left),getHeight(root->right))+1;
}


void L(TreeNode &root){
    TreeNode temp = root->right;
    root->right = temp->left;
    temp->left = root;
    updateHeight(root);
    updateHeight(temp);
    root = temp;
}


void R(TreeNode &root){
    TreeNode temp = root->left;
    root->left = temp->right;
    temp->right = root;
    updateHeight(root);
    updateHeight(temp);
    root = temp;
}

void insert(TreeNode &root,int val){
    if (root == NULL) {
        root = newnode(val);
//        root->val = val;
//        root->left = root->right = NULL;
        return;
    }
    if (val < root->val) {
        insert(root->left, val);
        updateHeight(root);
        if (getBalance(root) == 2) {
            if (getBalance(root->left) == 1) {
                R(root);
            }else if(getBalance(root->left) == -1){
                L(root->left);
                R(root);
            }
        }
    }else{
        insert(root->right, val);
        updateHeight(root);
        if (getBalance(root) == -2) {
            if (getBalance(root->right) == -1) {
                L(root);
            }else if(getBalance(root->right) == 1){
                R(root->right);
                L(root);
            }
        }
    }
}

TreeNode create(vector<int> v){
    TreeNode root = NULL;
    for (int i=0; i<v.size(); i++) {
        insert(root, v[i]);
    }
    return root;
}

int main(){
    int n;
    scanf("%d",&n);
    vector<int> v;
    for (int i=0; i<n; i++) {
        int a;
        scanf("%d",&a);
        v.push_back(a);
    }
    TreeNode root = create(v);
    printf("%d\n",root->val);
}