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1. Preorder traversal of binary tree Force buckle OJ link Give you the root node of the binary tree, root, and return the preorder traversal of its node value. /** * Definition for a binary tree node. * public class TreeNode { * int val; * TreeNode left; * TreeNode right; * TreeNode() {} * TreeNode(int val) { t ...

A. Integer Diversity Count the number of figures with different absolute values in all figures. Only when the number of absolute values is less than 2 #include<bits/stdc++.h> using namespace std; typedef long long ll; const int inf=0x3f3f3f3f; const int N=200100; int n,m,t; int w[N]; int cw[N]; int main(){ cin>>t; while(t--) ...

Bibliography: data structure course (Fifth Edition), edited by Li Chunbao Computer experiment of data structure (Chapter II) I Time complexity: Find elements with sequence number i(1 ≤ i ≤ n)Find the first element with a value of xInsert a new element as the first elementInsert the new element as the last elementInsert the i(2 ≤ i &l ...

Learn about today's record stack Stack Stack (stack) A stack is an ordered list of Filo first in last out. Stack is a special linear table that restricts the insertion and deletion of elements in a linear table to the same end of the linear table. The end that allows insertion and deletion is the changing end, which is called the top of t ...

Class description public class Hashtable<K,V> extends Dictionary<K,V> implements Map<K,V>, Cloneable, Serializable This class implements a hash table that maps keys to values. Any non empty object can be used as a key or value. To successfully store and retrieve objects from the hash table, the objects used as keys must imp ...

1. Bubble sorting The basic idea of Bubble Sorting is to compare the values of adjacent elements from front to back (starting from the elements with smaller subscripts) through the sequence to be sorted, and exchange if the reverse order is found, so that the elements with larger values gradually move from front to back, just like bubbles unde ...

Dictionary tree Concept of dictionary tree This section is mainly for reference Reference link Dictionary tree is also called Trie tree and prefix tree. As the name suggests, it is a data structure that maintains strings. Dictionary tree, as the name suggests, is a tree about "dictionary". That is, it is a storage method for ...

1, Title Requirements Give you a matrix with m rows and n columns. Please return all the elements in the matrix in a clockwise spiral order.Example 1: Input: matrix = [[1,2,3],[4,5,6],[7,8,9]] Output:[1,2,3,6,9,8,7,4,5] Example 2: Input: matrix = [[1,2,3,4],[5,6,7,8],[9,10,11,12]] Output:[1,2,3,4,8,12,11,10,9,5,6,7] Tips: m == mat ...

📢 preface 🌻🌻🌻🌻🌻🌻🌻🌻🌻🌻🌻🌻🌻🌻🌻🌻🌻🌻🌻🌻🌻🌻🌻🌻🌻🌻🌻🌻🌻🌻🌻🌻🌻🌻🌻🌻🌻🌻🌻🌻🌲 Punching out an algorithm problem every day is not only a learning process, but also a sharing process 😜🌲 Tip: the problem-solving programming languages in this column are C# and Java🌲 To maintain a state of learning every day, let's wo ...

Stack push and stack sequence Title Description: Review the basic structure of the stack: The stack structure is first in first out, last in first out Stack in sequence: [1,2,3,4,5] stack out sequence [4,5,3,2,1], does it belong to the same stack in and out sequence? There may be hints in the stack: Idea: Use a stack simulati ...