Python实现的常用排序方法

1.冒泡排序,相邻位置比较大小,将比较大的(或小的)交换位置
def maopao(a):
    for i in range(0,len(a)):
        for j in range(0,len(a)-i-1):
            if a[j]>a[j+1]:
                temp = a[j+1]
                a[j+1] = a[j]
                a[j] = temp
                #print(a)
        #print(a)
    print(a)
2.选择排序,遍历选择一个最小的数与当前循环的第一个数交换
def xuanze(a):
    for i in range(0,len(a)):
        k=i
        temp = a[i]
        for j in range(i,len(a)):
            if a[j]<temp:
                temp = a[j]
                k = j
        a[k] = a[i]
        a[i] = temp
    print(a)
 
3.快速排序:将子段的第一个元素做为中值,先从右向左遍历,如过比中值大high-1,如果比中值小,将这个值放到low那里。
然后从左向右开始遍历,如果左侧的比中值大,将他放到high那里。当low>=high时,将中值的值赋给low
 
1).以下为参照公众号中的做法:
a =[7,1,3,2,6,54,4,4,5,8,12,34]
def sort(a,low,high): 
    while low < high:
        temp = a[low]
        while low < high and a[high]>=temp:
            high = high-1
        a[low]=a[high]
        while low<high and a[low]<temp:
            low = low+1
        a[high]=a[low]           
        a[low]=temp
    return low
def quicksort(a,low,high):
    if low<high:
        middle = sort(a,low,high)
        quicksort(a,low,middle)
        quicksort(a,middle+1,high)
        print(a)
sort(a,0,len(a)-1)
quicksort(a,0,len(a)-1)
print(a)
 
2).以下是参照网上的做法:
#在做快速排序时一直各种问题,是因为地柜那里没有考虑清楚,一直把low的值赋值为0了,
#实际上应该是不固定的low值,他每个子循环不定。
a =[7,1,3,2,6,54,4,4,5,8,12,34]
def sort(a,low,high): 
    while low < high:
        temp = a[low]
        while low < high and a[high]>=temp:
            high = high-1
        while low<high and a[high]<temp:
            a[low]=a[high]           
            low =low+1
            a[high]=a[low]
        a[low]=temp
    return low
def quicksort(a,low,high):
    if low<high:
        middle = sort(a,low,high)
        quicksort(a,low,middle)
        quicksort(a,middle+1,high)
        print(a)
sort(a,0,len(a)-1)
quicksort(a,0,len(a)-1)
print(a)
 
 
4插入排序:从左向右遍历,依次选取数值,从数值的左侧从右向左遍历,选择第一个比他小的数值的右侧插入该数值,其他数值依次向后赋值
#插入排序
a =[7,1,3,2,6,54,4,4,5,8,12,34]
for i in range(0,len(a)-1):
    temp=a[i+1]
    j=i+1
    while j>=0 and temp<a[j-1]:
        j=j-1      
        print(j)
    if j>=-1:
        k= i+1
        while k>=j:
            a[k]=a[k-1]
            k=k-1
            print(a)
        a[j]=temp
print(a)
 
插入排序方法2,用到了列表的a.insert(1,2)和清楚a[2:3]=[],这样可以少用一个循环
a =[7,1,3,2,6,54,4,4,5,8,12,34]
for i in range(1,len(a)-1):
    temp=a[i]
   
    j=i-1
    while j>=0 and temp<=a[j]:
        print(temp)
        j=j-1
    if j >=-1:
        a[i:i+1]=[]
        a.insert(j+1,temp)
        print(a)
print(a)
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