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题目链接：http://codeforces.com/contest/762/problem/D 多多分析状态；这个很明了 阅读全文
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C. Mahmoud and a Message Mahmoud wrote a message s of length n. He wants to send it as a birthday present to his friend Moaz who likes strings. He wro 阅读全文
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E. Game of Stones Sam has been teaching Jon the Game of Stones to sharpen his mind and help him devise a strategy to fight the white walkers. The rule 阅读全文