常见排序算法的python实现

def bubble_sort(arry):
    n = len(arry)                   #获得数组的长度
    for i in range(n):
        for j in range(1,n-i):
            if  arry[j-1] > arry[j] :       #如果前者比后者大
                arry[j-1],arry[j] = arry[j],arry[j-1]      #则交换两者
    return arry

def select_sort(ary):
    n = len(ary)
    for i in range(0,n):
        min = i                             #最小元素下标标记
        for j in range(i+1,n):
            if ary[j] < ary[min] :
                min = j                     #找到最小值的下标
        ary[min],ary[i] = ary[i],ary[min]   #交换两者
    return ary

def insert_sort(ary):
    n = len(ary)
    for i in range(1,n):
        if ary[i] < ary[i-1]:
            temp = ary[i]
            index = i           #待插入的下标
            for j in range(i-1,-1,-1):  #从i-1 循环到 0 (包括0)
                if ary[j] > temp :
                    ary[j+1] = ary[j]
                    index = j   #记录待插入下标
                else :
                    break
            ary[index] = temp
    return ary

def shell_sort(ary):
    n = len(ary)
    gap = round(n/2)       #初始步长 , 用round四舍五入取整
    while gap > 0 :
        for i in range(gap,n):        #每一列进行插入排序 , 从gap 到 n-1
            temp = ary[i]
            j = i
            while ( j >= gap and ary[j-gap] > temp ):    #插入排序
                ary[j] = ary[j-gap]
                j = j - gap
            ary[j] = temp
        gap = round(gap/2)                     #重新设置步长
    return ary

def merge_sort(ary):
    if len(ary) <= 1 : return ary
    num = int(len(ary)/2)       #二分分解
    left = merge_sort(ary[:num])
    right = merge_sort(ary[num:])
    return merge(left,right)    #合并数组

def merge(left,right):
    '''合并操作，
    将两个有序数组left[]和right[]合并成一个大的有序数组'''
    l,r = 0,0           #left与right数组的下标指针
    result = []
    while l<len(left) and r<len(right) :
        if left[l] < right[r]:
            result.append(left[l])
            l += 1
        else:
            result.append(right[r])
            r += 1
    result += left[l:]
    result += right[r:]
    return result

def quick_sort(ary):
    return qsort(ary,0,len(ary)-1)

def qsort(ary,left,right):
    #快排函数，ary为待排序数组，left为待排序的左边界，right为右边界
    if left >= right : return ary
    key = ary[left]     #取最左边的为基准数
    lp = left           #左指针
    rp = right          #右指针
    while lp < rp :
        while ary[rp] >= key and lp < rp :
            rp -= 1
        while ary[lp] <= key and lp < rp :
            lp += 1
        ary[lp],ary[rp] = ary[rp],ary[lp]
    ary[left],ary[lp] = ary[lp],ary[left]
    qsort(ary,left,lp-1)
    qsort(ary,rp+1,right)
    return ary

def heap_sort(ary) :
    n = len(ary)
    first = int(n/2-1)       #最后一个非叶子节点
    for start in range(first,-1,-1) :     #构造大根堆
        max_heapify(ary,start,n-1)
    for end in range(n-1,0,-1):           #堆排，将大根堆转换成有序数组
        ary[end],ary[0] = ary[0],ary[end]
        max_heapify(ary,0,end-1)
    return ary


#最大堆调整：将堆的末端子节点作调整，使得子节点永远小于父节点
#start为当前需要调整最大堆的位置，end为调整边界
def max_heapify(ary,start,end):
    root = start
    while True :
        child = root*2 +1               #调整节点的子节点
        if child > end : break
        if child+1 <= end and ary[child] < ary[child+1] :
            child = child+1             #取较大的子节点
        if ary[root] < ary[child] :     #较大的子节点成为父节点
            ary[root],ary[child] = ary[child],ary[root]     #交换
            root = child
        else :
            break