擅长:python、mysql、java
<p>只是使用<code>collections.defaultdict(int)</code>的另一种方法</p>
<pre><code>from collections import defaultdict
l = [(2,'x'),(-5,'y'),(-3,'x')]
d_dict = defaultdict(int)
for k, v in l:
d_dict[v]+=k
[(v,k) for k,v in d_dict.items()]
#Output:
#[(-1, 'x'), (-5, 'y')]
</code></pre>