## Numerical prediction based on SEIR model

The dream linkage of winter and summer vacation may be over. The recent digital simulation competition just has a topic about the epidemic situation of the new crown. So I want to take this opportunity to personally analyze the protagonist of this dream linkage, COVID-19. Parameter estimation method? The topic requires us to analyze and predict ...

## Several common sorting algorithms

Several common sorting algorithms What is the stability of the algorithm? Definition of stability: If the relative position of two equal numbers before and after sorting is unchanged, the algorithm is stable. So what's the benefit of stability? Sort from one key and then from another. The results of the first key sort can be used by the sec ...

## Farewell to bubble sorting, we talk about selection sorting

Farewell to bubble sorting, we talk about selection sorting This is what I wrote before Bubble sort I hope you can follow my title after reading these two blogs. The problem of bubble sort In this post, I talked about some of the features of bubble sorting After the first round of swapping, there is no guarantee that the array is ordered The l ...

## Optimal algorithm in machine learning

In machine learning, there are many problems that do not have an analytic solution or have an analytic solution but require a lot of computations (for example, the least squares solution of overdetermined problems). For such problems, we usually choose to solve them by an iterative optimization method. Negative gradient methods and Newton-type ...

## Introduction to red and black trees, and how concurrent HashMap balances red and black trees

Concurrent HashMap Basics 1. Concurrent HashMap maintains a Node array (JDK1.8) and stores the head nodes of each Node list. 2. When the length of the linked list exceeds 8, concurrent HashMap will consider converting the linked list to a red black tree, but not necessarily. 3. When the length of the linked list exceeds 8, but the length ...

## Long position! Do you really know why MySQL doesn't recommend uuid or snowflake id as primary key?

preface When designing tables in mysql, the official recommendation of MySQL is not to use uuid or discontinuous and non repeated snowflake id(long shape and unique, single machine incremental), but continuous and self increasing primary key id. the official recommendation is auto_ Then why not use uuid? What are the disadvantages of using uui ...

## Dynamic programming -- the shortest path

1, Problem description When doing LeetCode, we encountered the problem of dynamic planning. In Wikipedia, dynamic planning is explained as follows: A method of solving complex problems by decomposing the original problem into relatively simple subproblems. Dynamic programming is often applied to problems with overlapping subproblems and optimal ...

## Techniques for simulating processes

One type of algorithmic question is called the simulation process. This algorithmic question occurs very frequently in an interview because it is relatively simple and the code size is generally not long.Because they do not have a more fixed framework, they can also test the programmatic thinking of candidates.When you encounter an algorithm pr ...

## Notes on algorithms 7. Sorting out basic algorithms of binary tree

catalog Basic algorithm of binary tree 1.1 traversal of binary tree 1.1.1 definition of binary tree node 1.1.2 recursive implementation of order first, order in order and then order traversal 1.1.3 non recursive implementation of ordinal traversal 1.1.4 traversal of binary tree by layer 1.2 serialization and deserialization of binary tree ...

## Algorithm notes Chapter 4 Summary

sort Select sort void selectSort(){ for(int i=0;i<=n;i++){ int k=i; for(int j=i;j<=nlj++){ if(A[j]<A[K]){ k=j; } } int temp=A[i]; A[i]=A[k]; A[k]=temp; } } Insert sort int A[maxn],n; void insertSort(){ for(int i=2;i<=n;i++){//Sort n- ...