擅长:python、mysql、java
<p>调用<code>dict.__init__()</code>不会初始化类。对<code>super</code>的正确调用应该如下所示:</p>
<pre><code>def __init__(self, pm):
super(ProbabilityMass, self).__init__(pm)
# Input requirements
...
</code></pre>
<p>顺便说一下,您的<code>isNonnegative()</code>方法也不正确。更改为:</p>
<pre><code>def isNonnegative(self):
return all(d >= 0 for d in self.values())
</code></pre>