54 lines
3.3 KiB
Markdown
54 lines
3.3 KiB
Markdown
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# What is Data Structures and Algorithms?
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## Definition of Algorithm
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*Algorithm* is a set of instructions or operations to solve a problem (or a set of problems) in a finite amount of time. Algorithms have the following characteristics:
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- The problem is clear, and the input and output definitions are clear.
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- Deterministic, that is, the same input will always produce the same output.
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- Feasible, that is, it can be completed in a finite number of steps, a finite amount of time, and a finite amount of memory space.
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- Independent of programming languages, in other words, it can be implemented in multiple languages.
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## Definition of Data Structure
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*Data Structure* is a way of organizing and storing data in a computer. In order to improve the performance of data storage and operation, the design principles of data structures are:
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- Occupying as little space as possible, saving computer memory.
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- Data operations should be as fast as possible, including data access, addition, deletion, update, etc.
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- Provide concise data representation and logical information to facilitate efficient operation by algorithms.
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Data structure design is a process full of compromises, this means that if you get an advantage in one aspect, you will have to make a compromise in another aspect. For example, linked lists are more convenient for data addition and deletion than arrays, but they sacrifice the speed of data access; graphs provide more logical information than linked lists, but occupy more memory space.
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## Relationship between Data Structures and Algorithms
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*Data Structures* and *Algorithms* are highly related and tightly integrated, which are shown in the following:
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- Data structures are the foundation of algorithms. Data structures provide structured data storage and corresponding methods for manipulating data.
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- Algorithms are the stage for data structures to show their advantages. Data structures only store information, and only with algorithms can they solve specific problems.
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- Algorithms have corresponding optimal data structures. Given an algorithm, it can be implemented based on different data structures, and the final execution efficiency may vary greatly.
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<p align="center"> Fig. Relationship between data structures and algorithms </p>
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If we compare *Data Structures and Algorithms* to *LEGO*, we can get the corresponding relationship shown in the following table.
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<div class="center-table" markdown>
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| Data Structures & Algorithms | LEGO |
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| ------------------------- | -------------------------------------- |
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| Input data | LEGO blocks |
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| Data structure | The way blocks piece together (including size, shape, connection interface, etc.) |
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| Algorithm | The steps to piece all the blocks together to get the desired model |
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| Output data | A LEGO model |
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</div>
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!!! tip "A conventional abbreviation"
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In discussions, we usually abbreviate *Data Structures and Algorithms* as *Algorithms*. For example, the algorithm problems on LeetCode, actually involve both data structures and algorithms.
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