<p>[“a”,“a”,“a”,“B”,“B”]</p>
<p>词典
{A':3,
“B”:3}</p>
<p>我做了下面这样的事情,但我觉得有一个更快/更短的方法吗</p>
<pre><code>frequencyMap = dict()
letters = ["A","A","A","B","B","B"]
for letter in letters:
if letter not in frequencyMap:
frequencyMap[letter] = 0
frequencyMap[letter] += 1
</code></pre>