排序算法总结

 

1、直接插入排序

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def insert_sort(alist):     """插入排序"""     n = len(alist)     for j in range(1,n):         i = j         while i > 0:             if alist[i] < alist[i-1]:                 alist[i],alist[i-1] = alist[i-1],alist[i]                 i -= 1             else:                 break   if __name__ == "__main__":     l = [451, 122, 12, 455, 48, 48, 524, 65, 99, 1225]     print(l)     insert_sort(l)     print(l)

2、希尔排序

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#Author:liuyang   def shell_sort(alist):     """希尔排序"""     n = len(alist)     gap = n // 2     while gap > 0:         #插入算法，唯一的区别就是gap         for j in range(gap,n):             i = j             while i > 0:                 if alist[i] < alist[i - gap]:                     alist[i], alist[i - gap] = alist[i - gap], alist[i]                     i -= gap                 else:                     break         gap //= 2   if __name__ == "__main__":     l = [451, 122, 12, 455, 48, 48, 524, 65, 99, 1225]     print(l)     shell_sort(l)     print(l)

　　

3、直接选择排序

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# Author:liuyang def select_sort(alist):     """选择排序"""     n = len(alist)     for j in range(0, n - 1):  # j 0 ~ n-2         min_index = j         for i in range(j + 1, n):             if alist[min_index] > alist[i]:                 min_index = i         alist[j], alist[min_index] = alist[min_index], alist[j]

　　

4、冒泡排序

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#Author:liuyang   def bubble_sort(alist):     """冒泡排序"""     n = len(alist)     for j in range(0,n-1):      #产生0到n-2,一共n-1个数         count = 0         for i in range(0,n-1-j):             if alist[i] > alist[i+1]:                 alist[i],alist[i+1] = alist[i+1],alist[i]                 count += 1         if count == 0:             return     # i 0 ~ n-2 range(0,n-1) j = 0 # i 0 ~ n-3 range(0,n-1-1) j = 1 # i 0 ~ n-4 range(0,n-1-2) j = 2 # j = n   range(0,n-1-j)   if __name__ == "__main__":     l = [451, 122, 12, 455, 48, 48, 524, 65, 99, 1225]     print(l)     bubble_sort(l)     print(l)

5、快速排序

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#Author:liuyang def quick_sort(alist,first,last):     """快速排序"""     if first >= last:         return     mid_value = alist[first]     low = first     high = last       while low < high:         while low < high and alist[high] >= mid_value:             high -= 1         alist[low] = alist[high]           while low < high and alist[low] < mid_value:             low += 1         alist[high] = alist[low]       alist[low] = mid_value       #对左边进行快速排序     quick_sort(alist,first,low-1)     #对右边进行快速排序     quick_sort(alist,high+1,last)   if __name__ == "__main__":     l = [451, 122, 12, 455, 48, 48, 524, 65, 99, 1225]     print(l)     quick_sort(l,0,len(l)-1)     print(l)

　　

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#Author:liuyang def quick_sort(alist):     if len(alist) < 2:         return alist        #基线条件     else:         pivot = alist[0]         less = [i for i in alist[1:] if i <= pivot]    #所有小于基准值的子数组         greater = [i for i in alist[1:] if i > pivot]    #所有大于基准值的子数组         return quick_sort(less) + [pivot] + quick_sort(greater)     if __name__ == "__main__":     l = [451, 122, 12, 455, 48, 48, 524, 65, 99, 1225]     print(l)     print(quick_sort(l))

　　

6、归并排序

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#Author:liuyang def merge_sort(alist):     """归并排序"""     n = len(alist)     if n == 1:         return alist     mid = n // 2     left_li = merge_sort(alist[:mid])     right_li = merge_sort(alist[mid:])       left_point,right_point = 0,0     result = []       while left_point < len(left_li) and right_point < len(right_li):         if left_li[left_point] < right_li[right_point]:             result.append(left_li[left_point])             left_point += 1         else:             result.append(right_li[right_point])             right_point += 1       result += left_li[left_point:]     result += right_li[right_point:]     return result     if __name__ == "__main__":     l = [451, 122, 12, 455, 48, 48, 524, 65, 99, 1225]     print(l)     new_list = merge_sort(l)     print(l)     print(new_list)

　

　

 

另附大佬实现的各种排序代码（此代码来源于：数据结构与算法 Python语言描述 作者：裘宗燕）

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""" 排序算法 """   from random import randrange, randint     class Record:     def __init__(self, key, datum):         self.key = key         self.datum = datum       def __str__(self):         return "R(" + str(self.key) + ", " + str(self.datum) + ")"     def printR(lst):     print("[" + ", ".join(map(str, lst)) + "]")   #### 简单插入排序 ##def insert_sort(lst) : ##    for i in range(1, len(lst)): # 开始时片段[0:1]已排序 ##        x = lst[i] ##        j = i ##        while j > 0 and lst[j-1].key > x.key: ##            lst[j] = lst[j-1]  # 反序逐个后移元素至确定插入位置 ##            j -= 1 ##        lst[j] = x ## ## ##def test1(n): ##    l1 = [Record(randint(1, 20), i) for i in range(n)] ##    printR(l1) ##    insert_sort(l1) ##    printR(l1)     #### 简单选择排序 # def select_sort(lst): #    for i in range(len(lst)-1): #        k = i #        for j in range(i, len(lst)): #            if lst[j].key < lst[k].key: #                k = j #        if i != k: #            lst[i], lst[k] = lst[k], lst[i] # # # def test2(n): #    l1 = [Record(randint(1, 20), i) for i in range(n)] #    printR(l1) #    select_sort(l1) #    printR(l1)     #### 简单起泡排序 ##def bubble_sort(lst): ##    for i in range(len(lst)): ##        for j in range(1, len(lst)-i): ##            if lst[j-1].key > lst[j].key: ##                lst[j-1], lst[j] = lst[j], lst[j-1]     #### 起泡排序，无逆序时提前结束 # def bubble_sort(lst): #    for i in range(len(lst)): #        found = False #        for j in range(1, len(lst)-i): #            if lst[j-1].key > lst[j].key: #                lst[j-1], lst[j] = lst[j], lst[j-1] #                found = True #        if not found: #            break # # # def test3(n): #    l1 = [Record(randint(1, 20), i) for i in range(n)] #    printR(l1) #    bubble_sort(l1) #    printR(l1)     #### 快速排序 # def quick_sort(lst): #    def qsort_rec(lst, l, r): #        if l >= r: #            return      # 分段中无记录或只有一个记录 #        i, j = l, r #        pivot = lst[i] #        while i < j:    # 找 pivot 的最终位置 #            while i < j and lst[j].key >= pivot.key: #                j -= 1  # 用 j 向左找小于 pivot 的记录移到左边 #            if i < j: #                lst[i] = lst[j] #                i += 1 #            while i < j and lst[i].key <= pivot.key: #                i += 1  # 用 i 向右找大于 pivot 的记录移到右边 #            if i < j: #                lst[j] = lst[i] #                j -= 1 #        lst[i] = pivot          # 将 pivot 存入其最终位置 #        qsort_rec(lst, l, i-1)  # 递归处理左半区间 #        qsort_rec(lst, i+1, r)  # 递归处理右半区间 # #    qsort_rec(lst, 0, len(lst)-1)  # 主函数调用 qsort_rec # # # def test4(n): #    l1 = [Record(randint(1, 20), i) for i in range(n)] #    printR(l1) #    quick_sort(l1) #    printR(l1)     #### 快速排序的另一种实现 # def quick_sort1(lst): #    def qsort(lst, begin, end): #        if begin >= end: #            return #        pivot = lst[begin].key #        i = begin #        for j in range(begin + 1, end + 1): #            if lst[j].key < pivot: # 发现一个小元素 #                i += 1 #                lst[i], lst[j] = lst[j], lst[i] # 小元素交换到前面 #        lst[begin], lst[i] = lst[i], lst[begin] # 枢轴元素就位 #        qsort(lst, begin, i - 1) #        qsort(lst, i + 1, end) # #    qsort(lst, 0, len(lst) - 1) # # # def test4(n): #    l1 = [Record(randint(1, 20), i) for i in range(n)] #    printR(l1) #    quick_sort1(l1) #    printR(l1)     #### 归并排序 # def merge_sort(lst): #    slen, llen = 1, len(lst) #    templst = [None] * llen #    while slen <= llen: #        merge_pass(lst, templst, llen, slen) #        slen *= 2 #        merge_pass(templst, lst, llen, slen)  # 结果存回原位 #        slen *= 2 # # # def merge_pass(lfrom, lto, llen, slen): #    i = 0 #    while i + 2 * slen < llen:  # 归并长slen的两段 #        merge(lfrom, lto, i, i + slen, i + 2 * slen) #        i += 2 * slen #    if i + slen < llen:  # 剩下两段，后段长度小于slen #        merge(lfrom, lto, i, i + slen, llen) #    else:   # 只剩下一段，复制到表lto #        for j in range(i, llen): #            lto[j] = lfrom[j] # # # def merge(lfrom, lto, low, m, high): #    i, j, k = low, m, low #    while i < m and j < high:  # 反复复制两段首记录中较小的 #        if lfrom[i].key <= lfrom[j].key: #            lto[k] = lfrom[i] #            i += 1 #        else: #            lto[k] = lfrom[j] #            j += 1 #        k += 1 #    while i < m:     # 复制第一段剩余记录 #        lto[k] = lfrom[i] #        i += 1 #        k += 1 #    while j < high:  # 复制第二段剩余记录 #        lto[k] = lfrom[j] #        j += 1 #        k += 1 # # # def test5(n): #    l1 = [Record(randint(1, 20), i) for i in range(n)] #    printR(l1) #    merge_sort(l1) #    printR(l1)     #### 基数排序 #### 假设被排序仍是以记录类型 Record 为元素的表，其中 ####   关键码是数字 0 到 9 的序列（元组），长度 r 为参数 #### 排序中用 10 个 list 存储各关键码元素对应的序列 #### 一遍分配后收集回到原表，r 遍分配和收集完成排序工作   # def radix_sort(lst, r): #     rlists = [[] for i in range(10)] #     llen = len(lst) #     for d in range(-1, -r-1, -1): #         for j in range(llen): #             rlists[lst[j].key[d]].append(lst[j]) #         j = 0 #         for i in range(10): #             tmp = rlists[i] #             for k in range(len(tmp)): #                 lst[j] = tmp[k] #                 j += 1 #             rlists[i].clear() # # # def test6(n): #     lst = [Record(tuple((randrange(10) for j in range(3))), #                   i) for i in range(n)] #     printR(lst) #     radix_sort(lst, 3) #     printR(lst) #     print()     # if __name__ == '__main__': #     test1(15)