用Python实现常见排序算法

最简单的排序有三种：插入排序，选择排序和冒泡排序。这三种排序比较简单，它们的平均时间复杂度均为O(n^2)，在这里对原理就不加赘述了。贴出来源代码。

插入排序：
def insertion_sort(sort_list):
    iter_len = len(sort_list)
    if iter_len < 2:
        return sort_list
    for i in range(1, iter_len):
        key = sort_list[i]
        j = i - 1
        while j >= 0 and sort_list[j] > key:
            sort_list[j+1] = sort_list[j]
            j -= 1
        sort_list[j+1] = key
    return sort_list
冒泡排序：
def bubble_sort(sort_list):
    iter_len = len(sort_list)
    if iter_len < 2:
        return sort_list
    for i in range(iter_len-1):
        for j in range(iter_len-i-1):
            if sort_list[j] > sort_list[j+1]:
                sort_list[j], sort_list[j+1] = sort_list[j+1], sort_list[j]
    return sort_list
选择排序：
def selection_sort(sort_list):
    iter_len = len(sort_list)
    if iter_len < 2:
        return sort_list
    for i in range(iter_len-1):
        smallest = sort_list[i]
        location = i
        for j in range(i, iter_len):
            if sort_list[j] < smallest:
                smallest = sort_list[j]
                location = j
        if i != location:
            sort_list[i], sort_list[location] = sort_list[location], sort_list[i]
    return sort_list

平均时间复杂度为O(nlogn)的算法有：归并排序，堆排序和快速排序。

#快排
def quickSort(lists):
    if len(lists)<=1:
        return lists
    pivot = lists.pop()
    left = []
    right = []
    for i in lists:
        if i<pivot:
            left.append(i)
        else:
            right.append(i)
    return quickSort(left)+[pivot]+quickSort(right)
#归并排序
def mergesort(lists):
    if len(lists)<=1:
        return lists
    mid = int(len(lists)/2)
    left = lists[:mid]
    right = lists[mid:]
    mergesort(left)
    mergesort(right)
    return merge(left,right)
def merge(left,right):
    i,j = 0,0
    result = []
    while i<len(left) and j<len(right):
        if left[i]<=right[j]:
            result.append(left[i])
            i+=1
        else:
            result.append(right[j])
            j+=1
    while(i<len(left)):
        result.append(left[i])
        i+=1
    while(j<len(right)):
        result.append(right[j])
        j+=1
    return result

#排序算法集合
import random
#冒泡排序
def BubbleSort(lists):
    for i in range(0,len(lists)):
        for j in range(0,len(lists)-1-i):
            if lists[j]>lists[j+1]:
                lists[j],lists[j+1] = lists[j+1],lists[j]
    return lists
#选择排序
def selectionSort(lists):
    for i in range(len(lists)):
        min = i
        for j in range(i+1,len(lists)):
            if lists[j]<lists[min]:
                min = j
        if min != i:
            lists[min],lists[i] = lists[i],lists[min]
    return lists
#插入排序
def insertSort(lists):
    for i in range(1,len(lists)):
        key = lists[i]
        j = i-1
        while j>=0 and key<lists[j]:
            lists[j+1] = lists[j]
            j -= 1
        lists[j+1]=key

    return lists
#希尔排序
def shellSort(lists):
    count = len(lists)
    step = 2
    group = int(count/step)
    while group>0:
        for i in range(group):
            j = i+group
            while j<count:
                key = lists[j]
                k = j-group
                while k>=0:
                    if key<lists[k]:
                        lists[k+group]=lists[k]
                        lists[k] = key
                    k -= group
                j+=group
        group = int(group/2)
    return lists
#快排
def quickSort(lists):
    if len(lists)<=1:
        return lists
    pivot = lists.pop()
    left = []
    right = []
    for i in lists:
        if i<pivot:
            left.append(i)
        else:
            right.append(i)
    return quickSort(left)+[pivot]+quickSort(right)
#归并排序
def mergesort(lists):
    if len(lists)<=1:
        return lists
    mid = int(len(lists)/2)
    left = lists[:mid]
    right = lists[mid:]
    left = mergesort(left)
    right = mergesort(right)
    return merge(left,right)
def merge(left,right):
    i,j = 0,0
    result = []
    while i<len(left) and j<len(right):
        if left[i]<=right[j]:
            result.append(left[i])
            i+=1
        else:
            result.append(right[j])
            j+=1
    while(i<len(left)):
        result.append(left[i])
        i+=1
    while(j<len(right)):
        result.append(right[j])
        j+=1
    return result
#归并排序
def mergeSort(lists):

    mid = int(len(lists)/2)
    left,right = lists[:mid],lists[mid:]
    if len(left)>1:left = mergeSort(left)
    if len(right)>1:right = mergeSort(right)
    res = []
    # while left and right:
    #     if left[-1]>=right[-1]:
    #         res.append(left.pop())
    #     else:
    #         res.append(right.pop())
    # res.reverse()
    #return (left or right) + res
    while left and right:
        if left[0]<=right[0]:
            res.append(left.pop(0))
        else:
            res.append(right.pop(0))
    return res+(left or right)
def adjust_heap(lists,i,size):
    lchild = 2*i+1
    rchild = 2*i+2
    max = i
    if i<size/2:
        if lchild<size and lists[lchild]>lists[max]:
            max = lchild
        if rchild>size and lists[rchild]>lists[max]:
            max = rchild
        if max != i:
            lists[max],lists[i] = lists[i], lists[max]
            adjust_heap(lists,max,size)
def build_heap(lists,size):
    for i in range(0,int(size/2))[::-1]:
        adjust_heap(lists,i,size)
def heap_sort(lists):
    size = len(lists)
    build_heap(lists,size)
    for i in range(0,size)[::-1]:
        lists[0],lists[i] = lists[i],lists[0]
        adjust_heap(lists,0,i)
    return lists

if __name__ =='__main__':
    lists = [random.randint(1,20) for n in range(10)]
    #print(lists)
    #print(sorted(lists))
    #print(lists)
    #print(BubbleSort(lists))
    #print(lists)
    #print(selectionSort(lists))
    #print(lists)
    #print(insertSort(lists))
    #print(lists)
    #print(shellSort(lists))
    #print(lists)
    #print(mergesort(lists))
    #print(lists)
    #print(quickSort(lists))
    #print(lists)
    #print(mergeSort(lists))
    print(lists)
    print(heap_sort(lists))