349. intersection of two arrays#12
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nodchip
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Jul 21, 2025
| public: | ||
| std::vector<int> intersection(std::vector<int>& nums1, std::vector<int>& nums2) { | ||
| std::vector<int> result; | ||
| std::sort(nums1.begin(), nums1.end()); |
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関数を呼び出す側にとって、関数に渡した値が関数の中で書き換わってしまうことは、通常意図しないことが多いと思います。コピーを作ってからソートしたほうが良いと思います。
なお、業務で書くコードの場合、関数の引数のうち、複合型で値を変更しないものについては、 const 参照で渡すことが多いと思います。また、関数の出力を引数で返す場合は、非 const 参照にすることが多いと思います。
また、一つの引数が入力と出力の両方を兼ねることはあまりないように感じます。何らかの理由によりもしそうする場合は、関数のコメントで明示的に説明すると思います。
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コメントありがとうございます。Leetcodeの形式をそのままコピーしてしまっていました。意識するようにします。
確かに確認してみるとstd::vector::push_backなども引数はconst参照になっていました。
| std::sort(nums2.begin(), nums2.end()); | ||
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| std::set_intersection(nums1.begin(), nums1.end(), nums2.begin(), nums2.end(), std::back_inserter(result)); | ||
| result.erase(std::unique(result.begin(), result.end()), result.end()) |
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入力を std::set に入れてから std::set_intersection() すると、この行が不要になります。
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ありがとうございます。単純にソートするよりそのほうが簡潔で効率がよさそうですね。
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This Problem
https://leetcode.com/problems/intersection-of-two-arrays/description/