快速排序算法分析

def quick(list,start,end):
    if start>=end:
        return
    low = start
    high = end
    key = list[low]
    while start<end:
        while start<end and list[end]>key:
            end-=1
        list[start]=list[end]
        while start<end and list[start]<=key:
            start+=1
        list[end]=list[start]
    list[end] = key
    quick(list,low,start-1)
    quick(list,start+1,high)