快速排序应用代码

def quick_sort(alist, start, end):
“”“快速排序”""
if start >= end:
return
mid = alist[start]
left = start
right = end

# left与right未重合， 就向中间移动
while left < right:
    while left < right and alist[right] >= mid:
        right -= 1
    alist[left] = alist[right]
    while left < right and alist[left] < mid:
        left += 1
    alist[right] = alist[left]
    # 从循环退出后，left与right相遇， 即left==right
    alist[left] = mid

    # 对左边部分执行快速排序
    quick_sort(alist, start, left-1)

    # 对右边部分执行快速排序
    quick_sort(alist, left+1, end)
print(alist)

if name == ‘main’:
li = [54, 26, 93, 17, 77, 31, 44, 55, 20]
print(li)
quick_sort(li, 0, len(li)-1)
print(li)