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147 lines
3 KiB
Markdown
Executable file
147 lines
3 KiB
Markdown
Executable file
---
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comments: true
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---
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# 10.1. 线性查找
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「线性查找 Linear Search」是一种最基础的查找方法，其从数据结构的一端开始，依次访问每个元素，直到另一端后停止。
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## 10.1.1. 算法实现
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线性查找实质上就是遍历数据结构 + 判断条件。比如，我们想要在数组 `nums` 中查找目标元素 `target` 的对应索引，那么可以在数组中进行线性查找。
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=== "Java"
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```java title="linear_search.java"
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[class]{linear_search}-[func]{linearSearchArray}
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```
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=== "C++"
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```cpp title="linear_search.cpp"
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[class]{}-[func]{linearSearchArray}
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```
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=== "Python"
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```python title="linear_search.py"
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[class]{}-[func]{linear_search_array}
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```
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=== "Go"
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```go title="linear_search.go"
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[class]{}-[func]{linearSearchArray}
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```
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=== "JavaScript"
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```javascript title="linear_search.js"
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[class]{}-[func]{linearSearchArray}
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```
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=== "TypeScript"
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```typescript title="linear_search.ts"
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[class]{}-[func]{linearSearchArray}
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```
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=== "C"
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```c title="linear_search.c"
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```
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=== "C#"
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```csharp title="linear_search.cs"
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[class]{linear_search}-[func]{linearSearchArray}
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```
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=== "Swift"
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```swift title="linear_search.swift"
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[class]{}-[func]{linearSearchArray}
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```
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=== "Zig"
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```zig title="linear_search.zig"
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[class]{}-[func]{linearSearchArray}
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```
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再比如，我们想要在给定一个目标结点值 `target` ，返回此结点对象，也可以在链表中进行线性查找。
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=== "Java"
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```java title="linear_search.java"
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[class]{linear_search}-[func]{linearSearchLinkedList}
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```
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=== "C++"
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```cpp title="linear_search.cpp"
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[class]{}-[func]{linearSearchLinkedList}
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```
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=== "Python"
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```python title="linear_search.py"
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[class]{}-[func]{linear_search_linkedlist}
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```
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=== "Go"
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```go title="linear_search.go"
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[class]{}-[func]{linearSearchLinkedList}
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```
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=== "JavaScript"
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```javascript title="linear_search.js"
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[class]{}-[func]{linearSearchLinkedList}
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```
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=== "TypeScript"
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```typescript title="linear_search.ts"
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[class]{}-[func]{linearSearchLinkedList}
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```
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=== "C"
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```c title="linear_search.c"
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```
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=== "C#"
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```csharp title="linear_search.cs"
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[class]{linear_search}-[func]{linearSearchLinkedList}
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```
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=== "Swift"
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```swift title="linear_search.swift"
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[class]{}-[func]{linearSearchLinkedList}
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```
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=== "Zig"
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```zig title="linear_search.zig"
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[class]{}-[func]{linearSearchLinkedList}
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```
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## 10.1.2. 复杂度分析
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**时间复杂度 $O(n)$** ：其中 $n$ 为数组或链表长度。
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**空间复杂度 $O(1)$** ：无需使用额外空间。
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## 10.1.3. 优点与缺点
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**线性查找的通用性极佳**。由于线性查找是依次访问元素的，即没有跳跃访问元素，因此数组或链表皆适用。
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**线性查找的时间复杂度太高**。在数据量 $n$ 很大时，查找效率很低。
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