112. Path Sum #17
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112. Path Sum #17
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ryosuketc
reviewed
Aug 4, 2025
| if root is None: | ||
| return False | ||
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| node_and_val = [(root, root.val, root.val)] |
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root.val は root からアクセスできるのでスタックに積む必要はないと思います。node_and_path_sum などにするとよさそうですね (最初、2, 3 番目の要素が何を示しているのか戸惑いました)。
| node_and_val = [(root, root.val, root.val)] | ||
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| while node_and_val: | ||
| node, val, sum = node_and_val.pop() |
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組み込みの sum を上書きしているので、避けたほうがいいですね。path_sum とするか、やむを得なければ sum_ でしょうか。
https://peps.python.org/pep-0008/#descriptive-naming-styles
single_trailing_underscore_: used by convention to avoid conflicts with Python keyword, e.g. :
tkinter.Toplevel(master, class_='ClassName')
| return False | ||
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| targetSum = targetSum - root.val | ||
| if targetSum == 0 and root.left is None and root.right is None: |
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細かいしどちらでもいいですが、
if root.left is None and root.right is None and targetSum == 0:
...if root.left is None and root.right is None:
if targetSum == 0:
...としたくなりますね。葉であるかどうかが前提条件なおで先にチェックしたいです。
tokuhirat
reviewed
Aug 4, 2025
| if node.left is None and node.right is None: | ||
| if sum == targetSum: | ||
| return True | ||
| if node.right: |
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None であるか確認している場合とそうでない場合が混在している点が気になりました。
また、L20 では left を先に書いていて、L23-26 では right を先に書いている点も少し気になりました。
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112. Path Sum
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