108. Convert Sorted Array to Binary Search Tree #25
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nodchip
reviewed
Jul 10, 2024
| # self.val = val | ||
| # self.left = left | ||
| # self.right = right | ||
| class Solution: |
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こちらの解法は思いつきませんでした。おそらく step1・3 が想定解な気がします。
hayashi-ay
reviewed
Jul 10, 2024
| class Solution: | ||
| def sortedArrayToBST(self, nums: List[int]) -> Optional[TreeNode]: | ||
| def build_bst(left: int, right: int) -> Optional[TreeNode]: | ||
| if right - left == 0: return None |
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if left >= right: return None 好みかもしれないですが。自分はこちらのほうが好きです。
| - height-balancedなので、木の高さはlogオーダー | ||
| - よって再帰処理で書いてOK | ||
| - time: O(n), space: O(n) | ||
| - dummyの値を持ったcomplete binary treeを構築して、inorder traversalしながら値をセットしても良さそう |
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あ、なるほど〜
inorder traversalの性質をうまく使ってますね 👀
fhiyo
reviewed
Jul 11, 2024
Comment on lines
+30
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| - Boxについて | ||
| - https://github.com/fhiyo/leetcode/pull/26#discussion_r1652886883 | ||
| - 初めて見た | ||
| - 参照をラップしている？一般的な概念なのかな？後ほど詳しく調べる |
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一般的な概念なのかはよく分からないです...オブジェクトを持てればListでも何でも構わないですが、何となくこのときは独自クラスを作りました
ちなみにBoxの元ネタはRustのBox で、ヒープ上に値を確保するときに使うやつです
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元ネタはRustなんですね。ありがとうございます！
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Box はもうちょっと広い古い概念かとおもいます。Java でもよく使ってましたね。
https://en.wikipedia.org/wiki/Boxing_(computer_science)
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ありがとうございます。Boxing, ふわっとしたイメージしか無かったのでありがたいです
(Java触ったことあるなら知っていて良い概念ですね...)
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問題へのリンク
https://leetcode.com/problems/convert-sorted-array-to-binary-search-tree/description/
次に解く問題
112. Path Sum
README.mdへ頭の中の言語化と記録をしています。