CoCalc provides the best real-time collaborative environment for Jupyter Notebooks, LaTeX documents, and SageMath, scalable from individual users to large groups and classes!
CoCalc provides the best real-time collaborative environment for Jupyter Notebooks, LaTeX documents, and SageMath, scalable from individual users to large groups and classes!
Path: blob/master/Day16-20/code/example02.py
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"""1排序 - 冒泡排序、选择排序、归并排序、快速排序2冒泡排序 - O(n ** 2):两两比较,大的下沉335, 97, 12, 68, 55, 73, 81, 40435, 12, 68, 55, 73, 81, 40, [97]512, 35, 55, 68, 73, 40, [81]612, 35, 55, 68, 40, [73]7...8选择排序 - O(n ** 2):每次从剩下元素中选择最小9-----------------------------------------10归并排序 - O(n * log_2 n) - 高级排序算法1135, 97, 12, 68, 55, 73, 81, 4012[35, 97, 12, 68], [55, 73, 81, 40]13[35, 97], [12, 68], [55, 73], [81, 40]14[35], [97], [12], [68], [55], [73], [81], [40]15[35, 97], [12, 68], [55, 73], [40, 81]16[12, 35, 68, 97], [40, 55, 73, 81]17[12, 35, 40, 55, 68, 73, 81, 97]18-----------------------------------------19快速排序 - 以枢轴为界将列表中的元素划分为两个部分,左边都比枢轴小,右边都比枢轴大2035, 97, 12, 68, 55, 73, 81, 402135, 12, [40], 68, 55, 73, 81, 9722[12], 35, [40], 68, 55, 73, 81, [97]23[12], 35, [40], 55, [68], 73, 81, [97]24[12], 35, [40], 55, [68], 73, [81], [97]25"""262728class Person(object):29"""人"""3031def __init__(self, name, age):32self.name = name33self.age = age3435# def __gt__(self, other):36# return self.name > other.name3738def __str__(self):39return f'{self.name}: {self.age}'4041def __repr__(self):42return self.__str__()434445def select_sort(origin_items, comp=lambda x, y: x < y):46"""简单选择排序"""47items = origin_items[:]48for i in range(len(items) - 1):49min_index = i50for j in range(i + 1, len(items)):51if comp(items[j], items[min_index]):52min_index = j53items[i], items[min_index] = items[min_index], items[i]54return items555657# 函数的设计要尽量做到无副作用(不影响调用者)58# 9 1 2 3 4 5 6 7 859# 9 2 3 4 5 6 7 8 160# *前面的参数叫位置参数,传参时只需要对号入座即可61# *后面的参数叫命名关键字参数,传参时必须给出参数名和参数值62# *args - 可变参数 - 元组63# **kwargs - 关键字参数 - 字典64def bubble_sort(origin_items, *, comp=lambda x, y: x > y):65"""冒泡排序"""66items = origin_items[:]67for i in range(1, len(items)):68swapped = False69for j in range(i - 1, len(items) - i):70if comp(items[j], items[j + 1]):71items[j], items[j + 1] = items[j + 1], items[j]72swapped = True73if swapped:74swapped = False75for j in range(len(items) - i - 1, i - 1, -1):76if comp(items[j - 1], items[j]):77items[j], items[j - 1] = items[j - 1], items[j]78swapped = True79if not swapped:80break81return items828384def merge_sort(items, comp=lambda x, y: x <= y):85"""归并排序"""86if len(items) < 2:87return items[:]88mid = len(items) // 289left = merge_sort(items[:mid], comp)90right = merge_sort(items[mid:], comp)91return merge(left, right, comp)929394def merge(items1, items2, comp=lambda x, y: x <= y):95"""合并(将两个有序列表合并成一个新的有序列表)"""96items = []97index1, index2 = 0, 098while index1 < len(items1) and index2 < len(items2):99if comp(items1[index1], items2[index2]):100items.append(items1[index1])101index1 += 1102else:103items.append(items2[index2])104index2 += 1105items += items1[index1:]106items += items2[index2:]107return items108109110def quick_sort(origin_items, comp=lambda x, y: x <= y):111"""快速排序"""112items = origin_items[:]113_quick_sort(items, 0, len(items) - 1, comp)114return items115116117def _quick_sort(items, start, end, comp):118"""递归调用划分和排序"""119if start < end:120pos = _partition(items, start, end, comp)121_quick_sort(items, start, pos - 1, comp)122_quick_sort(items, pos + 1, end, comp)123124125def _partition(items, start, end, comp):126"""划分"""127pivot = items[end]128i = start - 1129for j in range(start, end):130if comp(items[j], pivot):131i += 1132items[i], items[j] = items[j], items[i]133items[i + 1], items[end] = items[end], items[i + 1]134return i + 1135136137def main():138"""主函数"""139items = [35, 97, 12, 68, 55, 73, 81, 40]140# print(bubble_sort(items))141# print(select_sort(items))142# print(merge_sort(items))143print(quick_sort(items))144items2 = [145Person('Wang', 25), Person('Luo', 39),146Person('Zhang', 50), Person('He', 20)147]148# print(bubble_sort(items2, comp=lambda p1, p2: p1.age > p2.age))149# print(select_sort(items2, comp=lambda p1, p2: p1.name < p2.name))150# print(merge_sort(items2, comp=lambda p1, p2: p1.age <= p2.age))151print(quick_sort(items2, comp=lambda p1, p2: p1.age <= p2.age))152items3 = ['apple', 'orange', 'watermelon', 'durian', 'pear']153# print(bubble_sort(items3))154# print(bubble_sort(items3, comp=lambda x, y: len(x) > len(y)))155# print(merge_sort(items3))156print(merge_sort(items3))157158159if __name__ == '__main__':160main()161162163