擅长:python、mysql、java
<p>此代码应提供所需的结果:</p>
<pre><code>result = []
keys = []
for key in self.landings:
if self.landings[key].color == "orange":
result.append(self.landings[key])
keys.append(key)
#at the end of the loop, "result" has all the orange planes
#at the end of the loop, "keys" has all the keys of the orange planes
number=len(result) #len(result) gives the number of orange planes
</code></pre>
<p>请注意,<code>len</code>在许多情况下适用于列表或字典中的x数。你知道吗</p>