English Study Three
COVID19
covid-19 epidemic forecast
Research on data-driven evaluation and prediction modeling of the development and spread of the new crown epidemic
Implement Data Structure By Python
Book structure ==> review
Data Structure
Graph
Graph database
Breadth first search
depth first search
Directed graph == Undirected graph
Binary Tree
Diagram/graph connecting everything
Only trees created with randomly shuffled data can be more balanced. If all inserted data is sorted, then the binary tree is out of balance.
If there are two sub nodes, the value of one sub node must be less than the sup node, and the value of the other sub node must be greater than the sup node.
Quick Select
Binary tree that makes everything faster
Doubly linked list
Worst case
Node-based data structure
Store data and next physical address
Recursion
Recursion in the eyes of computers
Fast recursive algorithm
QUEUE
Queue: first in, first out[FIFO]
The queue is also an ideal tool for processing asynchronous requests-it can ensure that the requests are executed in the order in which they are received. In addition, it is also often used to simulate real-world scenarios where things need to be processed in an orderly manner, such as airplanes waiting in line for take-off, patients waiting in line to see a doctor
insert data at the end
read data at the begin
remove data at the begin
STACK
insert data at the end
read data at the end
remove data at the end
Queue: last in, first out[LIFO]
Stack: all operations at the end of stack(STACK TOP)
When the order of data processing is opposite to the order of acceptance (LIFO), the stack is just right, like the “undo” action of a word processor, or the function call of a network application, it should be implemented with a stack
Stacks are rarely used in scenarios that require long-term retention of data, but are often used in various algorithms for processing temporary data
rules to follow: last in, first out
The end of the stack is called the top of the stack
The beginning of the stack is called the bottom of the stack
Its operations are at the end of the data structure
So far, our discussion of data structure has focused on its performance
Use stacks and queues to construct smart code
Hash Table
Hash table in two ways: one is the same value as the Value of Key, the general structure of this case we call for the Set (collection); and if the Key and Value corresponding to the content is not the same, then we call it One case is Map, which is commonly known as a collection of key-value pairs.
The ratio of the amount of data to the number of grids is called the load factor ==> (0.7)
The golden rule to avoid conflicts and save space: add ten grids for every seven elements added
Split link
Deal with conflicts
Alphabet
multiply list
A dictionary of fun and profitable synonyms
hash tables ==> dictionary (data structure)
Find a quick hash table查找快速哈希表
Intersection
Average situation
The role of O()
The two exchange positions
Sorting Algorithm
Select Sort
The two exchange positions
Compare the remaining values with the extracted values, find the minimum value and assign its index to the minimum value
Exchange the position of the extracted value and the minimum value according to the index
Bubble Sort
The essence of the sorting algorithm is a loop, so you only need to focus on the first loop.