PAT1123 Is It a Complete AVL Tree(AVL树&&完全二叉树)

题意:

给出一系列数,要求组成AVL树,最后层序输出,并且判断是否为一个完全二叉树

要点:

这题就是一个AVL树的插入和判断完全二叉树,之前分别都有出现过,AVL树的建立需要记忆。

#include<bits/stdc++.h>
using namespace std;
int cnt=0,n;
bool flag,vis;
vector<int> ans;

struct node{
    int key;
    node *left,*right;
};

node *rotateL(node *root){
    node *t=root->right;
    root->right=t->left;
    t->left=root;
    return t;
}

node *rotateR(node *root){
    node *t=root->left;
    root->left=t->right;
    t->right=root;
    return t;
}

node *rotateLR(node *root){
    root->left=rotateL(root->left);
    return rotateR(root);
}

node *rotateRL(node *root){
    root->right=rotateR(root->right);
    return rotateL(root);
}

int getHeight(node *root){
    if(root==nullptr) return 0;
    return max(getHeight(root->left),getHeight(root->right))+1;
}

node *insert(node *root,int key){
    if(root==nullptr){
        root=new node();
        root->key=key;
        root->left=root->right=nullptr;
    }else if(key<root->key){
        root->left=insert(root->left,key);
        if(getHeight(root->left)-getHeight(root->right)==2){
            if(key<root->left->key){
                root=rotateR(root);
            }else{
                root=rotateLR(root);
            }
        }
    }else{
        root->right=insert(root->right,key);
        if(getHeight(root->right)-getHeight(root->left)==2){
            if(key>root->right->key){
                root=rotateL(root);
            }else{
                root=rotateRL(root);
            }
        }
    }
    return root;
}

void print(node *root){
    queue<node *> que;
    que.push(root);
    while(!que.empty()){
        node *u=que.front();que.pop();
        if(u!=nullptr){
            ans.push_back(u->key);
            que.push(u->left);
            que.push(u->right);
            cnt++;
        }else{
            if(cnt!=n&&vis){
                flag=false;
                vis=false;
            }
        }
    }
}

int main(){
    int temp;
    scanf("%d",&n);
    node *root=nullptr;
    for(int i=0;i<n;i++){
        scanf("%d",&temp);
        root=insert(root,temp);
    }
    flag=true;
    vis=true;
    print(root);
    for(int i=0;i<ans.size();i++){
        if(i!=0) printf(" ");
        printf("%d",ans[i]);
    }
    if(flag){
        printf("\nYES\n");
    }else{
        printf("\nNO\n");
    }
    return 0;
}

 

posted @ 2018-08-25 17:04  seasonal  阅读(143)  评论(0编辑  收藏  举报