擅长:python、mysql、java
<p>您可以使用<a href="https://docs.python.org/3/library/collections.html#collections.Counter" rel="nofollow noreferrer">^{<cd1>}</a>:</p>
<pre><code>from collections import Counter
a = [1,2,3,2,1,5,6,5,5,5]
c = Counter(a)
res = [n for n, m in c.items() if m > 1]
print(res) # [1, 2, 5]
</code></pre>
<p>这样,您可以在列表上迭代一次,只在计数器上迭代一次。你知道吗</p>