擅长:python、mysql、java
<p>考虑</p>
<pre><code>def last_to_mid(s):
if len(s) == 1:
return s
if len(s)%2 == 0:
raise ValueError('expected string of odd length')
idx = len(s)//2
return f'{s[:idx]}{s[-1]}{s[idx+1:-1]}{s[idx]}'
</code></pre>
<p>操作如下:</p>
<pre><code>>>> last_to_mid('021')
'012'
>>> last_to_mid('0123x4567')
'01237456x'
>>> last_to_mid('1')
'1'
</code></pre>
<p>假设您有python3.6或更新版本的<a href="https://www.python.org/dev/peps/pep-0498/" rel="nofollow noreferrer">f-strings</a>。你知道吗</p>