擅长:python、mysql、java
<p>诀窍是使用列表切片来移动部分字符串。在</p>
<pre><code>def move_chars(s, index):
to_index = s.find('__') # index of destination underscores
chars = list(s) # make mutable list
to_move = chars[index:index+2] # grab chars to move
chars[index:index+2] = '__' # replace with underscores
chars[to_index:to_index+2] = to_move # replace underscores with chars
return ''.join(chars) # stitch it all back together
print(move_chars('ABAB__AB', 0))
print(move_chars('__ABABAB', 3))
</code></pre>