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F. Dasha and Nightmares Dasha, an excellent student, is studying at the best mathematical lyceum in the country. Recently, a mysterious stranger broug 阅读全文
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D. Remove Two Letters Dmitry has a string $s$, consisting of lowercase Latin letters. Dmitry decided to remove two consecutive characters from the str 阅读全文
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D. Maximum Subarray You are given an array $a_1, a_2, \dots, a_n$, consisting of $n$ integers. You are also given two integers $k$ and $x$. You have t 阅读全文