擅长:python、mysql、java
<p>第二个版本不正确,因为您将在左叶检查和右叶检查之间更新temp变量</p>
<pre><code>if root.left!=None:
temp+=[root.left.val] # temp updated here
self.helper(root.left,sum-root.val,res,temp)
if root.right!=None:
temp+=[root.right.val] # the updated value could be used here, which is wrong
self.helper(root.right,sum-root.val,res,temp)
</code></pre>