Minimum depth of binary tree #36
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Mike0121
reviewed
Jun 29, 2024
| node, depth = queue.popleft() | ||
| if not node.left and not node.right: | ||
| minimum_depth = depth | ||
| break |
Mike0121
reviewed
Jun 29, 2024
| def minDepth(self, root: Optional[TreeNode]) -> int: | ||
| if not root: | ||
| return 0 | ||
| minimum_depth = 0 |
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BFSで解くのであれば、leaf nodeを見つけた段階でdepthを返してしまって良いので、minimum_depthは不要かと思います。
fhiyo
reviewed
Jun 29, 2024
| def minDepth(self, root: Optional[TreeNode]) -> int: | ||
| # 幅優先で良い | ||
| minimum_depth = 0 | ||
| queue = deque([(root, 0)]) |
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phase2, 3だと変えてるので違和感あったのかなと思いますが、(node, nodeの一つ上の深さ) の組をキューに入れているのは理解するの難しいなと思いました。
Owner
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そうですね, phase1でわかりにくい+書くなら少しコメントを書く必要があると感じたのでphase2とphase3で変更しました
| if node.right and node.left: | ||
| queue.append((node.right, depth + 1)) | ||
| queue.append((node.left, depth + 1)) | ||
| elif node.right is not None: |
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(phase1のコードに突っ込み入れるのも野暮かもしれませんが) ここだけNoneを使って書いていて他は使ってないので違和感ありました。 elif node.right: で良さそうです
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ありがとうございます。その通りです...
oda
reviewed
Jun 30, 2024
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| if node.left: | ||
| queue.append((node.left, depth + 1)) | ||
| if node.right: | ||
| queue.append((node.right, depth + 1)) |
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None であっても気にせずに queue につっこんで、出てきたやつを continue するという手もあります。
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問題
111. Minimum Depth of Binary Tree