擅长:python、mysql、java
<p>如果不是,您应该返回<code>False</code>(否则它将返回<code>None</code>):</p>
<pre><code>def is_subsequence(sub, string):
if sub in string:
return True #if sub is a subsequence of str otherwise False
return False
</code></pre>
<p>甚至更好:</p>
^{pr2}$