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D. Super-Permutation A permutation is a sequence $n$ integers, where each integer from $1$ to $n$ appears exactly once. For example, $[1]$, $[3,5,2,1, 阅读全文
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F. Gardening Friends Two friends, Alisa and Yuki, planted a tree with $n$ vertices in their garden. A tree is an undirected graph without cycles, loop 阅读全文
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G2. Magic Triples (Hard Version) This is the hard version of the problem. The only difference is that in this version, $a_i \le 10^9$. For a given seq 阅读全文