## 7-7 create a binary tree for pre order sequence, output pre order sequence, middle order sequence and post order sequence, and output the number of leaf nodes (20 points)

I feel that I haven't learned the part of the tree very well. PTA encountered this problem and didn't write it out at first. After writing it, I found that it's actually very simple. Record it.
In fact, what I learned is the process of writing this question
That is, if you modify a structure with typedef, you can't define the structure variab ...

Posted by **webosb** on *Thu, 10 Mar 2022 14:33:12 +0100*

## Preorder traversal of leetcode 144 binary tree

Preorder traversal of binary tree
Title Description
Give you the root node of the binary tree, root, and return the preorder traversal of its node value.
Example 1:
Input: root = [1,null,2,3]
Output:[1,2,3]
Example 2:
Input: root = []
Output:[]
Example 3:
Input: root = [1]
Output:[1]
Method 1: recursion
For tree traversal, recursive method ...

Posted by **Kaizard** on *Wed, 09 Mar 2022 08:42:32 +0100*

## Binary tree data structure

Binary tree data structure
A tree whose element has at most 2 children is called a binary tree. Because each element in a binary tree can only have two children, we usually name them left and right children.
The binary tree node contains the following parts.
dataPointer to left childPointer to the right child
Binary tree includes:
Full bi ...

Posted by **phorman** on *Fri, 04 Mar 2022 11:57:41 +0100*

## Heap topK problem heap sorting priority queue object comparison problem

Heap topK problem - heap sorting
The concept of heap ❓
To represent a binary tree with the child's representation (a common representation for brushing questions) is essentially a chain storage. In fact, there is also a sequential storage for the storage of binary trees. To put it bluntly, take an array to store a binary tree, and the way to ...

Posted by **wendymelon** on *Thu, 03 Mar 2022 12:01:02 +0100*

## CSP2020-J-T3-expression

See you on the topic [CSP-J2020] expression - LuoguKnowledge point analysis:
Be able to parse the specified data in the string. This topic requires to parse numbers and logical operators from the string. For ex amp le, x123 only resolves 123 and records it as the 123rd variable. For the convenience of storage, you can save &, |,! Save as a ...

Posted by **Calamity-Clare** on *Thu, 24 Feb 2022 01:49:56 +0100*

## [binary tree] Morris traversal -- an traversal method without auxiliary space

preface
Traversal of binary tree is an unavoidable problem to solve the related problems of binary tree. Many problems are solved on the basis of traversal. According to different problems, we can use different traversal methods. According to the order of operations on the root node, it can be divided into:
Preorder traversal Middle order tra ...

Posted by **md7dani** on *Tue, 22 Feb 2022 09:55:53 +0100*

## UVA122 traverses Trees on the level

Title Description
input
(11,LL) (7,LLL) (8,R) (5,) (4,L) (13,RL) (2,LLR) (1,RRR) (4,RR) ()
(3,L) (4,R) ()
output
5 4 8 11 13 4 7 2 1
not complete
Idea 1: implement binary tree in pointer mode (chain storage) First define a structure, and then define a structure pointer root as the root node of the whole tree. If the left and right nodes ...

Posted by **henrygao** on *Sat, 19 Feb 2022 13:08:37 +0100*

## Recursive traversal and iterative traversal of binary tree

Binary tree
The so-called traversal refers to one and only one visit to each node in the tree along a search route. The operation of the access node depends on the specific application problem (for example, print the node content and add 1 to the node content). Traversal is one of the most important operations on a binary tree. It is a bin ...

Posted by **mikegzarejoyce** on *Fri, 11 Feb 2022 14:49:31 +0100*

## Interviewer: you don't even know how to restore the binary tree?

Recover the binary tree according to traversal
In the knowledge of binary tree, finding or traversing binary tree is a very important knowledge point. Because the author only paid attention to the traversal process of binary tree before, but ignored the importance of the inverse process of recovering binary tree from traversal. When I saw an a ...

Posted by **jarriola** on *Tue, 08 Feb 2022 10:29:10 +0100*

## [sword finger Offer] personal learning notes_ 68_ Nearest common ancestor of binary search tree

Brushing date: 7:49 am Sunday, May 30, 2021
Personal question brushing records and code collection are all from leetcode
After much discussion and consultation, we now intend to work in the direction of Java
The main answer language is Java
Title:
Sword finger Offer 68 - I. nearest common ancestor of binary search tree
Simple d ...

Posted by **npsari** on *Tue, 08 Feb 2022 02:50:43 +0100*