101 lines
3.4 KiB
Markdown
101 lines
3.4 KiB
Markdown
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---
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title: Freecodecamp Algorithm Insertion Sort Guide
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localeTitle: Freecodecamp算法插入排序指南
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---
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插入排序是基于[_比较_的排序](https://en.wikipedia.org/wiki/Comparison_sort) 。排序算法是基于比较的，如果它使用比较运算符（例如`less than`和`greated than` ）来查找两个数字之间的顺序。
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在这种排序技术中，我们始终在列表的较低位置维护一个已排序的子列表，然后我们从列表的其余部分中取一个元素并将其插入到正确的位置。我们这样做，直到所有元素都插入到子列表中。例如，在玩扑克牌时，我们会将牌分类。从左侧开始向右移动，我们继续将卡插入正确的位置直至结束。
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## 例
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在上面的示例中， `grey shaded`子列表始终排序。请注意，在开始的时候，子列表包含ONY一个元素， _平凡_排序。然后在每一步我们将`white shaded`子列表的最左边元素插入其正确的位置。
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因此，我们以这种方式对完整列表进行了排序。
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## 算法
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```
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Loop for i=0 to N-1:
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* Pick element array<a href='https://repl.it/CWZq' target='_blank' rel='nofollow'>i] and insert it into sorted sublist array[0...i-1]
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```
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## 复杂
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```
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Space complexity: O(1) // Auxillary/temporary space is used.
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Time complexity: O(n*n) // Two nested for loops are used.
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```
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## C ++实现
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```
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// Function to sort an array using insertion sort
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void insertionSort(int arr[], int n)
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{
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int i, key, j;
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for (i = 1; i < n; i++)
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{
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key = arr[i];
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j = i-1;
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/* Move elements of arr[0..i-1], that are greater than key,
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to one position ahead of their current position */
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while (j >= 0 && arr[j] > key)
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{
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arr[j+1] = arr[j];
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j = j-1;
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}
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arr[j+1] = key; // place element key at it's correct place
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}
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}
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int main()
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{
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// array to be sorted
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int arr[5] = {12, 11, 13, 5, 6};
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// call the insertion sort
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insertionSort(arr, 5);
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// prints sorted array ie 5 6 11 12 13
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for(int i=0; i<5; i++)
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std::cout << arr[i] << " ";
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return 0;
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}
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```
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：rocket：\[运行代码## Python实现
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```
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# Function to perform insertion sort
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def insertionSort(arr):
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# Traverse through array
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for i in range(1, len(arr)):
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key = arr<a href='https://forum.freecodecamp.com/images/emoji/emoji_one/rocket.png?v=3 ":rocket:"' target='_blank' rel='nofollow'>i]
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# Move elements of arr[0..i-1], that are greater than key,
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# to one position ahead of their current position
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j = i-1
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while j>=0 and key < arr[j] :
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arr[j+1] = arr[j]
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j -= 1
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arr[j+1] = key # place element key at it's correct place
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# array to be sorted
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arr = [12, 11, 13, 5, 6]
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# call the insertion sort
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insertionSort(arr)
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# prints sorted array ie 5 6 11 12 13
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for i in range(len(arr)):
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print(arr[i],end = ' ')
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```
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 [运行代码](https://repl.it/CWZi)
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## 好处
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1. 适用于几乎排序的小型数据和数据集。
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2. 简单实施。
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3. 通常比冒泡排序和选择排序更好，通常与合并排序一起使用。
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## 缺点
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1. 与合并排序，堆排序和快速排序相比，它在大型数据集上的效率较低。
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