python算法——快速排序算法

归并排序

def merge(li, low,mid, high):
    i = low
    j = mid+1
    ltmp = []
    while i<=mid and j <=high:
        if li[i]<li[j]:
            ltmp.append(li[i])
            i += 1
        else:
            ltmp.append(li[j])
            j += 1
    while i<=mid:
        ltmp.append(li[i])
        i += 1
    while j<=high:
        ltmp.append(li[j])
        j += 1
    li[low:high+1]=ltmp
# li = [1,5,7,8,9,2,5,7,10]
# merge(li,0,len(li)//2,len(li)-1)
# 本算法时间复杂度为O(n*logn)
def merge_sort(li,low,high):
    if low<high:
        mid = (low+high)//2
        merge_sort(li,low,mid)
        merge_sort(li,mid+1,high)
        merge(li,low,mid,high)


import time
def timer(func):
    def inner(*args,**kwargs):
        start = time.time()
        ret = func(*args,**kwargs)
        end = time.time()
        print(end-start)
        return ret
    return inner
@timer
def outer(li,low,high):
    merge_sort(li,low,high)
# import random
# li = list(range(1000))
# random.shuffle(li)
# print(li)
# outer(li,0,len(li)-1)   # 1000个数据费时0.004s
# print(li)

# li = list(range(10000))
# random.shuffle(li)
# print(li)
# outer(li,0,len(li)-1)   # 10000个数据费时0.05s
# print(li)