输入:string_reverse('abcdef')，返回：'fedcba'，写出你能想到的多种方法

1.使用字符串本身的翻转

def string_reverse1(text='abcdef'):

...    return text[::-1]

2.把字符串变为列表，用列表的reverse函数

>>> def string_reverse2(text='abcdef'):
...     new_text=list(text)
...     new_text.reverse()
...     return ''.join(new_text)
...
>>> print string_reverse2('abcdef')
fedcba

3.新建一个列表，从后往前取

>>> def string_reverse3(text='abcdef'):
...     new_text=[]
...     for i in range(1,len(text)+1):
...         new_text.append(text[-i])
...     return ''.join(new_text)
...
>>> print string_reverse3('abcdef')
fedcba

4.利用双向列表deque中的extendleft函数

>>> from collections import deque
>>> def string_reverse4(text='abcdef'):
...     d = deque()
...     d.extendleft(text)
...     return ''.join(d)
...
>>> print string_reverse4('abcdef')
fedcba

5.递归

>>> def string_reverse5(text='abcdef'):
...     if len(text)<=1:
...         return text
...     else:
...         return string_reverse5(text[1:]+text[0])
...
>>> print string_reverse5('abcdef')