【Arai60】21問目 104_Maximum Depth of Binary Tree#21
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shining-ai merged 2 commits intomainfrom Jun 30, 2024
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nodchip
reviewed
Mar 8, 2024
| class Solution: | ||
| def maxDepth(self, root: Optional[TreeNode]) -> int: | ||
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| def search_max_depth(node): |
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補助関数に分けても良いと思いますし、 maxDepth() と引数が同じため、 maxDepth() を直接再帰呼び出ししても良いと思いました。
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補助関数なしでできましたね。
rootがない時の戻り値がすぐ分かって、少し分かりやすくなると思いました。
hayashi-ay
reviewed
Mar 8, 2024
| def search_max_depth(node): | ||
| if not node: | ||
| return 0 | ||
| left_depth = search_max_depth(node.left) + 1 |
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left_depthという命名だと1足さないものな気がするんですよね。
left_depth = search_max_depth(node.left)
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深さだとrootが0カウントになってしまうということですね。
| node_depth_queue.append((node.left, depth + 1)) | ||
| if node.right: | ||
| node_depth_queue.append((node.right, depth + 1)) | ||
| max_depth = max(max_depth, depth) |
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BFSなのでmax取らなくても良いですね。
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| max_depth = max(max_depth, depth) | |
| max_depth = depth |
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一番最後のdepthが最大値で決まってますね。
max_depth変数作らずにdepthを返しても動きますね。
| max_depth = 1 | ||
| while stack_node_depth: | ||
| node, depth = stack_node_depth.pop() | ||
| if node.left: |
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好みの問題ですが、DFSの探索をするときは左側から見ていくのが自然な気がします。そうなるとstackに積む順番はnode.right, node.leftの順になります。
| @@ -0,0 +1,12 @@ | |||
| class Solution: | |||
| def maxDepth(self, root: Optional[TreeNode]) -> int: | |||
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問題
https://leetcode.com/problems/maximum-depth-of-binary-tree/