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mamo3gr
reviewed
Jan 17, 2026
| - https://docs.python.org/ja/3/library/functions.html#next | ||
| - https://docs.python.org/ja/3/library/functions.html#iter | ||
| - こういうのを使っていると上級者なんだろうなと思う | ||
| - 自分から書く選択肢に全くないのでなんとかしたい気持ち |
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私も知らなくて、調べて見つけた記憶があります。
dict.values() の一番目だけ欲しいけど、dict[1] とは書けないし、リストにしたら全要素コピーされて無駄だぞ…。何か方法があるんじゃないかな、と思って調べて突き当たりました。
私の経験からですが「何か方法があるんじゃないかな」は大抵の場合、方法があります。
mamo3gr
reviewed
Jan 17, 2026
| # @lc code=start | ||
| class Solution: | ||
| def firstUniqChar(self, s: str) -> int: | ||
| charactor_to_index = dict() |
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タイポしてますね。
Suggested change
| charactor_to_index = dict() | |
| character_to_index = dict() |
mamo3gr
reviewed
Jan 17, 2026
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| if charactor in charactor_to_index: | ||
| del charactor_to_index[charactor] | ||
| continue |
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頭から読んだとき、
- なぜ辞書でヒットしたら、そこからインデックスを消しちゃうんだ？
seen_charactersに含まれているかの確認は先にしなくていいのか？- 正解は、ユニークな文字だけ を辞書に保存したいから
seen_charactersには add しなくていいのか？- 実は、辞書に追加されているなら
seen_charactersにも入っている（これは後ろを読んで分かる）
- 実は、辞書に追加されているなら
のように、実際の動きを頭の中で頑張ってシミュレートする必要があり、短い行数のわりに大変に感じました。
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解く問題
First Unique Character In A String
次に解く問題
Subarray Sum Equals K