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fuga-98
reviewed
Apr 17, 2025
| ```python | ||
| class Solution: | ||
| def lengthOfLIS(self, nums: List[int]) -> int: | ||
| if nums is None: |
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Type関数を使っても良いかもしれません。
https://docs.python.org/ja/3.13/library/functions.html#type
oda
reviewed
Apr 18, 2025
| 変数名も含めて読みやすいように変えてみる。 | ||
| 最初の`if not nums`はこのままだと、numsにNoneが渡されても0を返してしまう。型ヒントからnumsにNoneは来ないことがわかっているが、 | ||
| もし来た場合、例外を出して早めにバグを顕在化してほしいなと思ったので、TypeErrorを出すようにした。 | ||
| あと最近Design by Contractとか防御的プログラミングの概念を本(Good Code, Bad Code)で学習したので、このあたりはチームの方針にもよるのかなと思った。 |
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「ユーザーフェイシングかどうか」など何を作っているかの状況によるかと思います。
https://docs.google.com/document/d/11HV35ADPo9QxJOpJQ24FcZvtvioli770WWdZZDaLOfg/edit?tab=t.0#heading=h.q026dzgqj28b
| tails = [] | ||
| for num in nums: | ||
| insert_position = bisect_left(tails, num) | ||
| if insert_position == len(tails): |
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私は、insert_position < len(tails) を条件にして上下入れ替えると思いますが、趣味の範囲ですね。
| return len(tails) | ||
| ``` | ||
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| ほかにも Fenwick Tree(Binary Indexed Tree)やセグメントツリーを使っても解けるらしいが、 |
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セグメントツリーはアイディアとしてどういう構造化を知っておくといいかもしれません(、私も、使わない問題でも発想の過程で使ったりします)が、知らなくても構わないくらいかと思います。パズルとして出題しやすい子なんですよ。
nodchip
reviewed
Apr 18, 2025
| left = 0 | ||
| right = len(tails) | ||
| while left < right: | ||
| mid = left + (right - left) // 2 |
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Python では int 型は多倍長整数で実装されています。そのため、オーバーフローを回避するような書き方はする必要がなく、 mid = (left + right) // 2 とシンプルに書いてしまって大丈夫だと思います。
hroc135
reviewed
Apr 19, 2025
| if nums is None: | ||
| raise TypeError("nums must be a List, not None") | ||
| if len(nums) == 0: | ||
| return 0 |
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https://leetcode.com/problems/longest-increasing-subsequence/description/