Algorithms and data structures---quick sort

def partition(li, left, right):
    tem = li[left]
    while left < right:
        while left < right and li[right] >= tem:
            right -= 1
        li[left] = li[right]
        while left < right and li[left] <= tem:
            left += 1
        li[right] = li[left]
    li[left] = tem
    return left

def quick_sort(li, left, right):
    if left < right:
        mid = partition(li, left, right)
        quick_sort(li, left, mid-1)
        quick_sort(li, mid+1, right)

li = [5,7,4,6,3,1,2,9,8]
quick_sort(li, 0, len(li)-1)
print(li)


# 快速排序的时间复杂度：O(nlogn)