str1 = "hello world!"print(str1[::-1])

from functools import reducestr1 = "hello world!"print(reduce(lambda x, y : y+x, str1))

str1 = "123455"def fun(string):  print("%s" % string == string[::-1] and "YES" or "NO")if __name__ == '__main__':  fun(str1)

str1 = "i love you!"print(str1.title())# 单词首字母大写print(str1.upper())# 所有字母大写print(str1.lower())# 所有字母小写print(str1.capitalize())# 字符串首字母大写

str1 = "i love you!"print(str1.split())# print(str1.split('/')) 则是以/为分隔符拆分

str1 = " i love you! "print(str1.strip())

str1 = ["123", "123", "123"]print(''.join(str1))

str1 = "python"list1 = [1, 2, 3]# 乘法表述print(str1 * 2)print(list1 * 2)# 输出# pythonpython# [1, 2, 3, 1, 2, 3]#加法表述str1 = "python"list1 = [1, 2, 3]str1_1 = ""list1_1 = []for i in range(2):  str1_1 += str1  list1_1.append(list1)print(str1_1)print(list1_1)# 输出同上

# 修改每个列表的值list1 = [2, 2, 2, 2]print([x * 2 for x in list1])# 展开列表list2 = [[1, 2, 3], [4, 5, 6], [1]]print([i for k in list2 for i in k])# 输出 [1, 2, 3, 4, 5, 6, 1]

x = 1y = 2x, y = y, x

from collections import Counterlist1 = ['1', '1', '2', '3', '1', '4']count = Counter(list1)print(count)# 输出 Counter({'1': 3, '2': 1, '3': 1, '4': 1})print(count['1'])# 输出 3print(count.most_common(1))# 出现最多次数的 # [('1', 3)]

str1 = "123456"# 方法一list_1 = list(map(int, str1))#方法二list_2 = [int(i) for i in str1]

str1 = "123456"list1 = [1, 2, 3, 4, 5]for i, j in enumerate(str1):  print(i, j)'''输出0 11 22 33 44 55 6'''str1 = "123456"list1 = [1, 2, 3, 4, 5]for i, j in enumerate(list1):  print(i, j)# 输出同上

import timestart = time.time()for i in range(1999999):  continueend = time.time()print(end - start)# 输出 0.08042168617248535

import sysstr1 = "123456"print(sys.getsizeof(str1))# 输出 55

dirt1 = {'a':2, 'b': 3}dirt2 = {'c':3, 'd': 5}# 方法一combined_dict = {**dirt1, **dirt2}print(combined_dict)# 输出 {'a': 2, 'b': 3, 'c': 3, 'd': 5}# 方法二dirt1 = {'a':2, 'b': 3}dirt2 = {'c':3, 'd': 5}dirt1.update(dirt2)print(dirt1)# 输出同上

list1 = [1, 2, 3, 4, 5, 6]print('%s' % len(list1) == len(set(list1)) and "NO" or "YES")