选择排序（Python）

Bertha 。 2023-01-03 04:19 168阅读 0赞

# 选择排序 #

<table> 
 <thead> 
 <tr> 
 <th>排序算法</th> 
 <th>平均时间复杂度</th> 
 <th>空间复杂度</th> 
 <th>稳定性</th> 
 </tr> 
 </thead> 
 <tbody> 
 <tr> 
 <td><a href="https://blog.csdn.net/weixin_41308573/article/details/112305019" rel="nofollow">冒泡排序</a></td> 
 <td> O ( n 2 ) O(n^2) O(n2)</td> 
 <td> O ( 1 ) O(1) O(1)</td> 
 <td>稳定</td> 
 </tr> 
 <tr> 
 <td><a href="https://blog.csdn.net/weixin_41308573/article/details/112305118" rel="nofollow">选择排序</a></td> 
 <td> O ( n 2 ) O(n^2) O(n2)</td> 
 <td> O ( 1 ) O(1) O(1)</td> 
 <td>不稳定</td> 
 </tr> 
 <tr> 
 <td><a href="https://blog.csdn.net/weixin_41308573/article/details/86178111" rel="nofollow">插入排序</a></td> 
 <td> O ( n 2 ) O(n^2) O(n2)</td> 
 <td> O ( 1 ) O(1) O(1)</td> 
 <td>稳定</td> 
 </tr> 
 <tr> 
 <td><a href="https://blog.csdn.net/weixin_41308573/article/details/86178111" rel="nofollow">希尔排序</a></td> 
 <td> O ( n log ⁡ 2 n ) O(n\log^2 n) O(nlog2n)</td> 
 <td> O ( 1 ) O(1) O(1)</td> 
 <td>不稳定</td> 
 </tr> 
 <tr> 
 <td><a href="https://blog.csdn.net/weixin_41308573/article/details/112305240" rel="nofollow">归并排序</a></td> 
 <td> O ( n log ⁡ 2 n ) O(n\log^2 n) O(nlog2n)</td> 
 <td> O ( n ) O(n) O(n)</td> 
 <td>稳定</td> 
 </tr> 
 <tr> 
 <td><a href="https://blog.csdn.net/weixin_41308573/article/details/86591978" rel="nofollow">快速排序</a></td> 
 <td> O ( n log ⁡ n ) O(n\log n) O(nlogn)</td> 
 <td> O ( log ⁡ n ) O(\log n) O(logn)</td> 
 <td>不稳定</td> 
 </tr> 
 <tr> 
 <td><a href="https://blog.csdn.net/weixin_41308573/article/details/86582643" rel="nofollow">堆排序</a></td> 
 <td> O ( n log ⁡ n ) O(n\log n) O(nlogn)</td> 
 <td> O ( 1 ) O(1) O(1)</td> 
 <td>不稳定</td> 
 </tr> 
 <tr> 
 <td><a href="https://blog.csdn.net/weixin_41308573/article/details/86632295" rel="nofollow">计数排序</a></td> 
 <td> O ( n + k ) O(n+k) O(n+k)</td> 
 <td> O ( k ) O(k) O(k)</td> 
 <td>稳定</td> 
 </tr> 
 <tr> 
 <td><a href="https://blog.csdn.net/weixin_41308573/article/details/86632295" rel="nofollow">基数排序</a></td> 
 <td> O ( n × k ) O(n\times k) O(n×k)</td> 
 <td></td> 
 <td>稳定</td> 
 </tr> 
 <tr> 
 <td><a href="https://blog.csdn.net/weixin_41308573/article/details/86632295" rel="nofollow">桶排序</a></td> 
 <td> O ( n ) O(n) O(n)</td> 
 <td> O ( m ) O(m) O(m)</td> 
 <td>稳定</td> 
 </tr> 
 </tbody> 
</table>

## 算法思路 ##

从待排序数列中选择最小的元素，将它与数列的第一个元素交换位置。再从数列剩下的元素中选择出最小的元素，将它与数组的第二个元素交换位置。不断进行这样的操作，直到将整个数组排序。

## 算法实现 ##

设置标志位记录待排序数列中最小元素的下标，每次遍历完成后都将最小元素放在已排序数列的末尾。

def selection_sort(arr):
 arr_len = len(arr)
 if arr_len < 2:
 return
 
 for i in range(arr_len):
 min_index = i
 for j in range(i+1, arr_len):
 if arr[min_index] > arr[j]:
 min_index = j
 if i != min_index:
 arr[i], arr[min_index] = arr[min_index], arr[i]

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