擅长:python、mysql、java
<p>我使用理解和集合来创建一个更易于理解的函数。在</p>
<pre><code>def find_four_substrings(a_str, sub_len=5, window=50, occurs=4):
'''
Given a string of any length return the set of substrings
of sub_length (default is 5) that exists exactly occurs
(default 4) times in the string, for a window (default 50)
'''
return set(a_str[i:i+sub_len] for i in range(len(a_str) - sub_len)
if a_str.count(a_str[i:i+sub_len], i, window) == occurs)
</code></pre>
<p>以及</p>
^{pr2}$
<p>退货</p>
<pre><code>set(['CGACA'])
</code></pre>