重点

冒泡排序:

lst = [88,5,8,6,1,23]
for a in range(len(lst)):   # 记录内部排序的次数
    i = 0
    while i < len(lst) - 1: # 把最大值移动到右端
        if lst[i] > lst[i+1]:   # 比较,
            lst[i], lst[i+1] = lst[i+1], lst[i] # 交换
        i = i + 1
print(lst)

文件改操作:

import os

with open('a.txt',mode='r',encoding='UTF-8') as a,\
    open('a1.txt',mode='w',encoding='UTF-8') as a1:
    for b in a:
        b1=b.replace('alex','SB')
        a1.write(b1)
os.remove('a.txt')
os.rename('a1.txt','a.txt')


求最大值和最小值:

def func(*args):
    m = args[0] # 假设第0项就是最大值
    mi = args[0]
    for el in args:
        if el > m:
            m = el # 当前这个元素比假设的那个大. 记录当前这个比较大的数
        if el < mi:
            mi = el
    return {"最大值":m, "最小值":mi}

print(func(5,7,12,1,46,87,3))

user_list=[
        {"name": "alex", "hobby": "抽烟"},
        {"name": "alex", "hobby": "喝酒"},
        {"name": "alex", "hobby": "烫头"},
        {"name": "wusir", "hobby": "喊麦"},
        {"name": "wusir", "hobby": "街舞"},
{"name": "alex", "hobby": "泡吧"},
        {"name":"太白", "hobby":"开车"}
         ]
# [{"name": "alex", "hobby_list": ["抽烟","喝酒","烫头","泡吧"]},{"name": "wusir", "hobby_list": ["喊麦", "街舞"]},]

result = [] # {'name': 'alex', 'hobby_list': ['抽烟']}
for user in user_list:
    # 1.判断是否在result里面存在了这个人, 如果存在. 把hobby_list添加一个hobby
    # 2.不存在. 创建一个新字典
    for new_user in result:
        if user['name'] == new_user['name']:
            new_user['hobby_list'].append(user['hobby'])
            break
    else:
        dic = {}
        dic["name"] = user['name']
        dic['hobby_list'] = [user['hobby']]
        result.append(dic)
print(result)

user_list = [{"name":"alex","hobby":"抽烟"},
             {"name":"alex","hobby":"喝酒"},
             {"name":"alex","hobby":"烫头"},
             {"name":"wusir","hobby":"喊麦"},
             {"name":"wusir","hobby":"街舞"},]

# 结果 = [{"name": "alex", "hobby_list": ["抽烟","喝酒","烫头",]},{"name": "wusir", "hobby_list": ["喊麦", "街舞"]},]

def main(user_list):
    dic = {}
    for i in user_list:
        if i['name'] not in dic:
            dic[i['name']] = {'name':i['name'],'hobby_list':[i['hobby']]}
        else:
            dic[i['name']]['hobby_list'].append(i['hobby'])
    return list(dic.values())
print(main(user_list))


迭代器:

lst=[5,2,0,1,3,1,4]
s=lst.__iter__()
while True:
    try:
        print(s.__next__())
    except StopIteration:
        break



归并排序算法:

lst1 = [1, 3, 7, 9, 12]
lst2 = [4, 8, 9, 13]
def merge(a, b):
    c = []
    h = j = 0
    while j < len(a) and h < len(b):
        if a[j] < b[h]:
            c.append(a[j])
            j += 1
        else:
            c.append(b[h])
            h += 1

    if j == len(a):
        for i in b[h:]:
            c.append(i)
    else:
        for i in a[j:]:
            c.append(i)

    return c
print(merge(lst1,lst2))




递归函数:

# 遍历树形结构
# import  os
# filePath = "d:\sylar\python_workspace"
#
# def read(filePath, n):
#     it = os.listdir(filePath)   # 打开文件夹
#     for el in it:
#         #  拿到路径
#         fp = os.path.join(filePath, el) # 获取到绝对路径
#         if os.path.isdir(fp):   # 判断是否是文件夹
#             print("\t"*n,el)
#             read(fp, n+1)    # 又是文件夹. 继续读取内部的内容 递归入口
#         else:
#             print("\t"*n,el)    # 递归出口
#
# read(filePath, 0)




二分查找:

# lst = [11,22,33,44,55,66,77,88,99,123,234,345,456,567,678,789,1111]
# n = 567
# left = 0
# right = len(lst) - 1
# count = 1
# while left <= right:
#     middle = (left + right) // 2
#     if n > lst[middle]:
#         left = middle + 1
#     elif n < lst[middle]:
#         right = middle - 1
#     else:
#         print(count)
#         print("存在")
#         print(middle)
#         break
#     count = count + 1
# else:
#     print("不存在")
lst = [11,22,33,44,55,66,77,88,99,123,234,345,456,567,678,789,1111]

def binary_search(left, right, n):
    middle = (left + right)//2
    if left > right:
        return -1
    if n > lst[middle]:
        left = middle + 1
    elif n < lst[middle]:
        right = middle - 1
    else:
        return middle
    return binary_search(left, right, n)
print(binary_search(0, len(lst)-1, 65) )


def binary_search(lst, n):
    left = 0
    right = len(lst) - 1
    middle = (left + right) // 2
    if right <= 0:
        print("没找到")
        return
    if n > lst[middle]:
        lst = lst[middle+1:]
    elif n < lst[middle]:
        lst = lst[:middle]
    else:
        print("找到了")
        return
    binary_search(lst, n)
binary_search(lst, 65)