算法----(4)快速排序

 1 def partion(nums, left, right):
 2     key = nums[left]
 3     while left < right:
 4         # right下标位置开始，向左边遍历，查找不大于基准数的元素
 5         while left < right and nums[right] >= key:
 6             right -= 1
 7         if left < right:  # 找到小于准基数key的元素,然后交换nums[left],nums[right]
 8             nums[left], nums[right] = nums[right], nums[left]
 9         else:   # left〉=right 跳出循环
10             break
11         # left下标位置开始，向右边遍历，查找不小于基准数的元素
12         while left < right and nums[left] < key:
13             left += 1
14         if left < right:  # 找到比基准数大的元素，然后交换nums[left],nums[right]
15             nums[right],nums[left] = nums[left],nums[right]
16         else:  # left〉=right 跳出循环
17             break
18     return left  #此时left==right 所以返回right也是可以的
19 
20 #realize from book "data struct" of author 严蔚敏
21 def quick_sort_standord(nums, left, right):
22     if left < right:
23         key_index = partion(nums, left, right)
24         quick_sort_standord(nums, left, key_index)
25         quick_sort_standord(nums, key_index+1, right)
26 
27 
28 if __name__ == ‘__main__‘:
29     nums = [5, 6, 4, 2, 3, 1]
30     print(nums)
31     quick_sort_standord(nums, 0, len(nums)-1)
32     print(nums)