206 reverse linked list#8
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wanwan87
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Jun 16, 2026
| return current_node | ||
| ``` | ||
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| （ 連結リストを逆向きに繋ぎ変えて、と言われたら普通はまず先にこれを思いつく気がしており、<https://1kohei1.com/leetcode/> を見てカテゴリーごとに問題を解いていることで思考が記載されているカテゴリーに引っ張られ過ぎているかもしれないと思った ） |
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最終的にいくつか選択肢が見えてその解き方を選択した根拠がある状態になっていれば良いと思うので、あまり気にしなくても良いのかなと思いました。（ちなみに自分も最初スタックで解きました。）
https://docs.google.com/document/d/11HV35ADPo9QxJOpJQ24FcZvtvioli770WWdZZDaLOfg/edit?tab=t.0#heading=h.q026dzgqj28b
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そうですね、そのための練習ということで気にしすぎずやっていきます。ありがとうございます。
| reversed_head = node | ||
| node = next_node | ||
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| return reversed_head |
| checking = checking.next | ||
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| num_nodes = len(nodes) | ||
| if num_nodes <= 1: |
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空リストの時だけnodes[0]で落ちると思うので1を含めず、以下のようなnodesの空判定だけのほうが意図が伝わりやすいかなと思いました。
if not nodes:
return None
num_nodes = len(nodes)
for i in range(num_nodes - 1, 0, -1):
nodes[i].next = nodes[i - 1]
nodes[0].next = None
return nodes[-1]
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ありがとうございます。そのように書いた方が良さそうです。
当初は range() をよくわかっておらず 正のステップで start >= stop (負のステップで start <= stop) の時の挙動を調べずになんとなくエラーになりそうと思って書いたのですが、単に空になるんですね。
メモ：https://docs.python.org/3/library/stdtypes.html#typesseq-range
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この問題：https://leetcode.com/problems/reverse-linked-list/
次の問題：https://leetcode.com/problems/kth-largest-element-in-a-stream/