Generally, the form page needs to fill in the mobile phone number. To verify whether the mobile phone number entered by the user is correct, we need to use the regular expression to match the mobile phone number segment. If it is in the operator number segment, the number is correct. Therefore, it is necessary to know the latest segment number ...
Added by lJesterl on Tue, 01 Mar 2022 21:32:39 +0200
Add: omit some questions. Here I think the questions that need to be posted are posted by me. The answers are different. You are welcome to express your views. I'll start with a brick to attract jade. Of course, the questions here are incomplete, and they will be supplemented in the follow-up.
2940. Byte string and string conversion
Added by LeslieHart on Tue, 01 Mar 2022 18:14:43 +0200
Definition and related concepts of tree
Start with the linked list and diagram
In the previous content, we learned the basic data structure of linked list. Single linked list is one of them. The structure form is as follows:
# Definition for the singly-linked list.
def __init__(self, val=0, next=Non ...
The reflection mechanism of Java is to know all the properties and methods of any class in the running state; For any object, we can call any of its methods and properties. Since we can get it, we can modify some type information; This function of dynamically obtaining information and dynamically calling object ...
Added by panic! on Tue, 01 Mar 2022 09:22:31 +0200
1. Data structure classification
Java data structures can be divided into two categories according to linearity and nonlinearity: ① Linear data structure: array, linked list, stack, queue ② Nonlinear data structure: tree, heap, hash table, graph
2. Linear data structure
Array is a data structure that stores elements in continuous ...
Added by Rose.S on Mon, 28 Feb 2022 15:25:59 +0200
112 path sum
Given a binary tree root and a value sum, judge whether there is a path where the sum of node values from the root node to the leaf node is equal to sum.
Enter a binary tree and a given integer, and output a Boolean value to indicate whether there are paths that meet the conditions.
Input: root = [5,4,8,11, null, 13,4,7,2, nu ...
Chapter I basic algorithm (I)
1, Content overview
Master the main ideas and have a deep understanding
Understand and memorize the code template (master the idea)
Template topic exercise
Understanding + memory
Quick rowMerge sort
2. Two points
Integer dichotomyFloating point binary
2, Quick sort
The main idea of ...
Added by orbitalnets on Mon, 28 Feb 2022 14:09:13 +0200
New solution of sequence query
The previous question "sequence query" said: A=[A0,A1,A2 ···, An] is a sequence composed of n+1 integers in the range of [0,N], which satisfies 0 = A0 < A1 < A2 < ·· < An < n. Based on sequence a, for any integer x within the range ...
Added by Eggzorcist on Mon, 28 Feb 2022 09:05:33 +0200
⭐ Introduction ⭐ ️
Hello, I'm Zhijie. There is only one month left for the countdown of the provincial competition of the Blue Bridge Cup. If you have practiced the real problem for nearly seven or eight years, you can obviously feel that the difficulty of the Blue Bridge Cup is becoming more and more difficult. Although it is far from being ...
Added by airdee on Mon, 28 Feb 2022 02:39:12 +0200
Binary sort tree
Requirements: for a sequence (7, 3, 10, 12, 5, 1, 9), it is required to query and add data efficiently
Basic introduction: Binary sort tree: BST: (Binary Sort(Search) Tree). For any non leaf node of the binary sort tree, the value of the left child node is required to be smaller than that of the current node, and the valu ...
Added by jefffan24 on Sun, 27 Feb 2022 05:43:02 +0200