選擇排序：

思想：每次選擇出最小的值依次放到最前面

代碼：

1 a = [9,1,22,31,45,3,6,2,11]
3 for i in range(len(a)-1):
4     index = i                                   #index標記最小的 值  假設第一個是最小的值
5     for j in range(i+1,len(a)):
6         if a[index] > a[j]: 
7             index = j                           #index 一直指向最小的值
8     a[i],a[index] = a[index],a[i]               #
 
讓a[index]  與  第[i]個值 互換  ，達到排序
9 print(a)
輸出結果：[1, 2, 3, 6, 9, 11, 22, 31, 45]

過程：

[9, 1, 22, 31, 45, 3, 6, 2, 11]
[1, 9, 22, 31, 45, 3, 6, 2, 11]
[1, 2, 22, 31, 45, 3, 6, 9, 11]
[1, 2, 3, 31, 45, 22, 6, 9, 11]
[1, 2, 3, 6, 45, 22, 31, 9, 11]
[1, 2, 3, 6, 9, 22, 31, 45, 11]
[1, 2, 3, 6, 9, 11, 31, 45, 22]
[1, 2, 3, 6, 9, 11, 22, 45, 31]
[1, 2, 3, 6, 9, 11, 22, 31, 45]

python 選擇排序