擅长:python、mysql、java
<p>你可以用听写器来做这件事,但你必须处理丢失的钥匙。而是使用<a href="https://docs.python.org/3/library/collections.html#collections.Counter" rel="nofollow noreferrer">^{<cd1>}</a>,它会自动将缺少的值视为<code>0</code></p>
<pre><code>from collections import Counter
tally = Counter()
for s in orders:
item, count = s.split(":")
tally[item] += int(count)
print(tally) # -> Counter({'screws': 35, 'nails': 35, 'brushes': 5})
</code></pre>
<p>您也可以使用<code>defaultdict(int)</code>,但是<code>Counter</code>是更好的作业工具</p>