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oda
reviewed
Jan 11, 2026
| // | ||
| // https://discord.com/channels/1084280443945353267/1233603535862628432/1238208008182562927 | ||
| // 不変条件を意識するのは大事。LinkedHashMap があれば、一つ気にしなければいけない要素を減らせる。 | ||
| // Dart の Map はデフォルトで LinkedHashMap になっているらしい。 |
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Java の LinkedHashMap は、要するに LinkedList + HashMap というデータ構造ですが、取り除くのは後でもいいので Queue と HashMap でもいけるという感じですね。
| // 自分は Set を用いて重複を判定していたが、counter での重複の方がコードが簡潔に済んで良い。 | ||
| // | ||
| // https://github.com/t0hsumi/leetcode/pull/15#discussion_r1930362913 | ||
| // 重複がないことの証明として、「左から読んだときと右から読んだときで、添字が変わらない」ことを使っていた。 |
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Python とかだと、文字を探すのはネイティブコードで走るので何度も走査していてもそこそこ速いと思います。
mamo3gr
reviewed
Jan 11, 2026
| var counter = <String, int>{}; | ||
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| for (var i = 0; i < s.length; i++) { | ||
| counter[s[i]] = (counter[s[i]] ?? 0) + 1; |
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解いた問題：https://leetcode.com/problems/first-unique-character-in-a-string/
次に解く問題：https://leetcode.com/problems/subarray-sum-equals-k/description/