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Prefix and brush question summary of leetcode 2 1 - region and retrieval - array immutable Title Link: Title Link stamp here!!! Idea: simple prefix sum. During initialization, use the sum array to store the prefix sum of the num array, and then calculate the interval sum from left to right in the num array, which can be obtained directly from ...

brief introduction    we all know that finally, as a part of exception handling, it can only be followed by a statement block immediately after the try/catch statement, indicating that this statement will be executed in the end "under normal circumstances" (whether there is an exception thrown or not), which is often used w ...

String Assignment Single quotation mark assignment a = 'this is a string' print(a) # this is a string``` Double Quote Assignment a = "this is a string" print(a) # this is a string Assignment of a three-quote string to a variable (multiple lines) Retains the newline format of the string # Triple Form a = '''this is a string''' prin ...

1. Main content of the article This blog is devoted to explaining the skills to encapsulate code in PyCharm and invoke it in JupyterNoteBook. Through the learning of this blog, taking KNN algorithm as an example, it is intended to grasp the skills of functional code in plain language. It takes about 5 minutes to read this blog. Note: the c ...

*** Output 'hello world', input input, output print print('hello world') Define variables, variable names and identifiers, which are composed of letters, numbers or underscores, and numbers cannot start. Variables cannot be named with keywords. Keywords - some identifiers with special functions or special meanings in python. a = 15 print(a ...

1, Meaning of subquery Meaning: select statements that appear in other statements are called subqueries or intra queries; The external query statement is called primary query or external query Classification: According to the location of sub query: After select: only scalar subqueries are supported After from: only table subqueries are ...

1: Input and output of C language and C++ IO stream In C language, there are three groups of input and output functions that we often use Input / outputOperation objectprintf/scanfConsolefprintf/fscanffilesprintf/sscanfCharacter array (buffer) The corresponding operations in C + + are as follows Input / outputOperation objectostream/isr ...

brief introduction This paper mainly explains the concept and basic use of axios. axios is currently one of the most popular ajax wrapper libraries for making it easy to send ajax requests. Supported functions: Issue an XMLHttpRequests request from the browser.From node.js makes an http request.Supports the Promise API.Ability to intercept ...

1. Basic concepts of sorting Sorting is an operation often carried out in the computer. Its purpose is to adjust a group of "unordered" record sequences to "ordered" record sequences. The purpose of sorting is to facilitate searching. If the whole sorting process can be completed without accessing external memory, th ...

ScopeA scope is the accessibility of variables, functions, and objects in certain parts of the runtime code. In other words, the scope determines the visibility of variables and other resources in the code block.function foo() { var a = 1 } foo() console.log(a) // Uncaught ReferenceError: inVariable is not definedThe above example can be un ...