Programming VIP

1, Title Requirements Give you an integer n, please generate and return all different binary search trees composed of N nodes with different node values from 1 to N, and you can return the answers in any order.Example 1: Input: n = 3 Output:[[1,null,2,null,3],[1,null,3,2],[2,1,3],[3,1,null,null,2],[3,2,null,1]] Example 2: Input: n = 1 ...

Valley: matrix rotation It can be found by observation that: For such a two column table, a 180 ° rotation of a 2x2 square is equivalent to the exchange of upper left and lower right, lower left and upper right And this exchange won't change anything? Two numbers in any column will not be changed! But it will change the positional rela ...

1, Overview of method recursion 1. What is method recursion The form in which a method calls itself directly or indirectly is called method recursion. As an algorithm, recursion is widely used in programming languages. 2. Recursive form Direct recursion: the method calls itself. Indirect recursion: the method calls other methods, and othe ...

introduction These two questions are mainly to investigate the mastery of binary tree traversal, that is, the original binary tree is derived from the front order and middle order, and the original binary tree is derived from the back order and middle order. Let's talk about the derivation process first; Preorder and middle order Know the preo ...

Recently, an infinite classification of data was processed, mainly using recursive functions. Of course, laravel has a more elegant Association query method. However, due to the need for many other secondary modifications to the data, the original recursive processing was adopted. At the same time, an image metaphor was used to illustrate the p ...

1. Establish the chain storage structure of binary tree (bracket representation) Algorithm idea: ① If ch = '(': it means that the node p just created has child nodes, and it needs to be stacked as the top node of the stack in order to establish the relationship between it and its child nodes (if a node has just been created, and the subsequ ...

preface Customize the regular expression rules, and then complete the implementation of the matching algorithm. 1, Title Please implement a function to match regular expressions containing '.' and '*'. The character '.' in the mode represents any character, and '/ *' represents that the character before it can appear any time (in ...

Recursive divide and Conquer - Example 2. Chessboard coverage 1, Problem description In a chessboard composed of 2^k x 2k squares, exactly one square is incomplete. There are 2(2k) positions of incomplete squares. Therefore, there are 2^(2k) kinds of incomplete chessboard with K ≥ 0 In the problem of chessboard coverage, it is required t ...

Split palindrome stringTitle Description: give you a string s. please divide s into some substrings so that each substring is a palindrome string. Returns s all possible segmentation schemes.A palindrome string is a string that reads the same forward and reverse.See LeetCode's official website for an example.Source: LeetCode Link: https://leet ...

subject Problem solving The increasing order of binary search tree is the order of middle order traversal. LeetCode426 transforms binary search tree into sorted two-way linked list & sword finger Offer 36 binary search tree and two-way linked list The simple version of question 426 needs to construct a two-way circular linked list ...