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Composite Pattern, also known as partial overall pattern, is used to treat a group of similar objects as a single object. The combination mode combines objects according to the tree structure, which is used to represent the partial and overall levels. This type of design pattern belongs to structural pattern, which creates a tree structure of o ...

Hello, everyone. Meet again. I'm Jun Quan.iReport is generally a design stage tool. Used to design the layout and content of the report. The dynamic generation of reports needs to be realized by programs (after all, the data of reports is dynamic and the quantity is very large, so it is impossible to manually generate them one by one in the way ...

​ Error details: Traceback (most recent call last): File "D:\software\Anaconda3\envs\swim\lib\site-packages\numpy\core\__init__.py", line 22, in <module> from . import multiarray File "D:\software\Anaconda3\envs\swim\lib\site-packages\numpy\core\multiarray.py", line 12, in <module> from . import overrides File "D:\sof ...

I introduction Design a data structure that supports the following operations under the average time complexity O(1). Note: duplicate elements are allowed. The collection contains the following three functions: A.insert(val): inserts the element val into the collection. B.remove(val): removes a val from the collection when it exists. C.ge ...

Title Description Number of schemes to reconstruct a tree thinking Construct the tree and verify the legitimacy of the tree The first is the second item in the description of scheme number condition in the title. If and only if it means that all number pairs in pairs have ancestor grandson relationship, and all nodes with ancestor g ...

Abstract: in Internet applications, high concurrency systems will face a major challenge, that is, a large number of stream high concurrency visits, such as tmall's double 11, JD 618, second kill, rush purchase promotion, etc. These are typical high concurrency scenarios with large traffic. This article is shared from Huawei cloud community& ...

Overview of Cocos2d-x physics engine   when we try to make a complex game, the game needs to simulate the situation of the real world, such as simulating the collision of two objects, simulating the object receiving gravity, etc. Do you need to use a physical engine   don't use a physics engine when your requirements are simple. Fo ...

We know the process of using the sql/database package of the standard library of Go language to operate the database. Although it is very convenient to use the sql/database package to operate the data, we need to write each SQL statement ourselves. Therefore, we may encapsulate it again for better use, and using the existing open source ORM fra ...

I Trees and forests • tree: one to many structure (1 to 0, 1 to 1, one to many), with a starting point 'root node' • node: a data element of the tree • children: one to many 'many' • subtree: a tree with a child node as its root • leaf nodes: nodes without children • forest: multiple trees II Binary tree ...

Reading needs a certain foundation, which is not suitable for people who first know Java. There are some concise languages, some knowledge points or a brush, and you don't know that you need to consult the materials in detail. The purpose of this article is to supplement some details of Java foundation, some slightly in-depth places and some pl ...