PATA1123题解

构造AVL树与层序遍历判断完全二叉树综合

//
//  main.cpp
//  PATA1123
//
//  Created by Phoenix on 2018/2/25.
//  Copyright © 2018年 Phoenix. All rights reserved.
//

#include <iostream>
#include <cstdio>
#include <queue>
#include <algorithm>
using namespace std;
int n, num[25];

struct node {
    int data, height;
    node *lchild, *rchild;
};

node* newnode(int x) {
    node* root = new node;
    root->data = x;
    root->height = 1;
    root->lchild = root->rchild = NULL;
    return root;
}

int getHeight(node* root) {
    if(root == NULL) return 0;
    else return root->height;
}

int getBalanceHeight(node* root) {
    return getHeight(root->lchild) - getHeight(root->rchild);
}

void updateHeight(node* root) {
    root->height = max(getHeight(root->lchild), getHeight(root->rchild)) + 1;
}

void L(node* &root) {
    node* temp = root->rchild;
    root->rchild = temp->lchild;
    temp->lchild = root;
    updateHeight(root);
    updateHeight(temp);
    root = temp;
}

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 x) {
    if(root == NULL) {
        root = newnode(x);
        return;
    }
    if(x < root->data) {
        insert(root->lchild, x);
        updateHeight(root);
        if(getBalanceHeight(root) == 2) {
            if(getBalanceHeight(root->lchild) == 1) {
                R(root);
            } else if(getBalanceHeight(root->lchild) == -1) {
                L(root->lchild);
                R(root);
            }
        }
    } else {
        insert(root->rchild, x);
        updateHeight(root);
        if(getBalanceHeight(root) == -2) {
            if(getBalanceHeight(root->rchild) == -1) {
                L(root);
            } else if(getBalanceHeight(root->rchild) == 1) {
                R(root->rchild);
                L(root);
            }
        }
    }
}

node* create(int data[], int n) {
    node* root = NULL;
    for(int i = 0; i < n; i++) {
        insert(root, data[i]);
        //printf("%d ", root->data);
    }
    return root;
}

void levelorder(node* root) {
    queue<node*> q;
    q.push(root);
    int k = 0;
    bool flag = true, flag1 = true;
    while(!q.empty()) {
        node* top = q.front();
        q.pop();
        if(top == NULL) flag1 = false;
        else {
            printf("%d", top->data);
            if(k < n - 1) printf(" ");
            else printf("\n");
            k++;
        }
        if(flag1 == false && top != NULL) flag = false;
        if(top) {
            q.push(top->lchild);
            q.push(top->rchild);
        }
    }
    if(flag == true) printf("YES\n");
    else printf("NO\n");
}

int main(int argc, const char * argv[]) {
    scanf("%d", &n);
    for(int i = 0; i < n; i++) {
        scanf("%d", &num[i]);
    }
    node* root = create(num, n);
    levelorder(root);
    return 0;
}