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Problem Description Claire and her little friend, ykwd, are travelling in Shevchenko's Park! The park is beautiful - but large, indeed. N feature spot 阅读全文
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树上面最长简单路（无环），就是树的直径问题 解决办法 一开始任取一个点u进行搜索查找出距离点u最远距离的点v和长度 第二次dfs则从第一次中的v找出距离点v最远距离的点的路径长度 Cow Marathon Description After hearing about the epidemic of 阅读全文
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Since Sonya has just learned the basics of matrices, she decided to play with them a little bit. Sonya imagined a new type of matrices that she called 阅读全文