擅长:python、mysql、java
<p>或者你需要<a href="http://docs.python.org/2/library/itertools.html#itertools.product" rel="nofollow">^{<cd1>}</a>:</p>
<pre><code>>>> import itertools
>>> [i for i in itertools.product(('', 'tag'), ('sha', 'md5'))]
[('', 'sha'), ('', 'md5'), ('tag', 'sha'), ('tag', 'md5')]
</code></pre>