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学习日志017--python的几种排序算法

冒泡排序

def bubble_sort(alist):
    i = 0
    while i<len(alist):
        j=0
        while j<len(alist)-1:
            if alist[j]>alist[j+1]:
                alist[j],alist[j+1] = alist[j+1],alist[j]
            j+=1

        i+=1

l = [2,4,6,8,0,1,3,5,7,9]
bubble_sort(l)
print(l)

选择排序

def select_sort(alist):
    i = 0
    while i<len(alist)-1:
        temp = i
        j=i+1
        while j<len(alist):
            if alist[temp]>alist[j]:
                temp = j
            j+=1
        if not temp == i:
            alist[i],alist[temp] = alist[temp],alist[i]
        i += 1
l = [6, 4, 5, 3, 8, 9, 2, 1, 7]
select_sort(l)
print(l)

 

直接排序

def insert_sort(alist):
    i=1
    while i<len(alist):
        temp = alist[i]
        j = i
        while j>0 and alist[j - 1] > temp:
            alist[j] = alist[j-1]
            j-=1
        alist[j] = temp
        i+=1
l = [2,4,6,8,0,1,3,5,7,9]
insert_sort(l)
print(l)

 快速排序

def part(alist,l,r):
    p = alist[l]

    while l<r:
        while l<r and alist[r]>p:
            r-=1
        alist[l] = alist[r]

        while l<r and alist[l]<p:
            l+=1
        alist[r] = alist[l]
    alist[l] = p

    return l

def quick_sort(alist,l,r):
    if l<r:
        p_index = part(alist, l, r)
        print(alist)
        quick_sort(alist,l,p_index-1)
        quick_sort(alist,p_index+1,r)

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

希尔排序

def shell_sort(alist):
    n = len(alist)
    gap = n//2
    while gap>0:
        for i in range(gap,n):
            temp = alist[i]
            j = i
            while alist[j-gap] > temp and j >= gap:
                alist[j] = alist[j-gap]
                j -= gap
            alist[j] = temp

        gap = gap // 2
    return arr

arr = [6, 4, 5, 3, 8, 9, 2, 1, 7]
print("排序前:", arr)
sorted_arr = shell_sort(arr)
print("排序后:", sorted_arr)

xmind 

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