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Description Given the finite multi set $A$ of $n$ pairs of integers, an another finite multi set $B$ of $m$ triples of integers, we define the product 阅读全文
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Description Ladies and gentlemen, please sit up straight. Don't tilt your head. I'm serious. For $n$ given strings $S_{1},S_{2},\cdots,S_{n}$, labelle 阅读全文
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Description Greg has an $m \times n$ grid of Sweet Lightbulbs of Pure Coolness he would like to turn on. Initially, some of the bulbs are on and some 阅读全文
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Description 给定一棵$N$个结点的树,结点用正整数$1 \dots N$编号,每条边有一个正整数权值。用$d(a, b)$表示从结点$a$到结点$b$路径上经过边的权值和,其中要求$a 第一行包含两个正整数$N,M$。 下面$N − 1$行,每行三个正整数$a, b, c (a, b \ 阅读全文