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Let's start with the conclusion: map uses 3 lines of code to solve the problem of 5 lines of code in the for loop, which is equivalent to a 40% increase in efficiency You can't learn without (I said) If you don't use it, you won't be able to use it Because you don't know the usage scenario, you can't use it because you haven't learned it ...

There are two data types in ECMAScript: basic data type and reference data type. Basic data type Basic data types are also called simple data types, which are Undefined, Null, Boolean, Number, String and Symbol. The basic data type is characterized by a fixed size of space in memory and stored on the stack. 1. Undefined type The undefined type ...

Queue is a first in first out ordered list, which can be realized by array or linked list (for example, Bank Queuing System) prerequisite: maxSize: queue capacity (length of array) arr: array of simulated queues front: points to the previous element of the queue header element, with an initial value of - 1 rear: refers to the element at th ...

Two dimensional array quick get start Please output the following graphics with a two-dimensional array 0 0 0 0 0 0 0 0 1 0 0 0 0 2 0 3 0 0 0 0 0 0 0 0 The code is as follows: package ArrayList_Practice; public class TwoDimensionalArray01 { public static void main(String[] args) { int arr[][] = {{0,0,0,0,0,0},{0,0,1,0,0,0}, {0,2, ...

queue Queue is a sequential list, which can be implemented by array (sequential storage) or linked list (linked storage).Follow the principle of first in, first out. That is, the data stored in the queue should be taken out first. After the deposit, it shall be taken out. Simulating queues using arrays The queue itself has a seque ...

In order from simple to difficult, break through the hurdles in turn (the title number is the serial number of leetcode) Main JAVA Source: https://leetcode-cn.com/ catalogue 1. Sum of two numbers (1) - hash table lookup 2. Delete duplicates in the ordered array (26) -- double pointers 3. Remove element (27) - Optimization of double pointe ...

1. Title Given a matrix with M x N elements (M rows, N columns), return all the elements in the matrix in the order of diagonal traversal, as shown in the following figure. Example: input: [ [ 1, 2, 3 ], [ 4, 5, 6 ], [ 7, 8, 9 ] ] output: [1,2,4,7,5,3,6,8,9] Explain: The total number of elements in a given matrix does not exce ...

The array object de duplication is completed. Let's look at the array de duplication. 1, The first method Use indexOf() and push() for array de duplication. The indexOf() method returns the first occurrence of a specified string value in the string. If no matching string is found, - 1 is returned. Note: the indexOf() method is case sens ...

Java programming exercise Day08 Check box control array Example description Check box control is often used in GUI program interface design. For example, many options can be added to the user's favorite program interface. If these options are entered through the GUI interface designer, it is very time-consuming, and the generated code ...

Common data structures and algorithm implementation (sorting / searching / array / linked list / stack / queue / tree / recursion / massive data processing / graph / bitmap / Java data structure) As the basic skills of programmers, data structures and algorithms must be studied steadily. The bottom layer of our common framework is all kinds ...