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Problem StatementWe have a directed graph with $N$ vertices, called Vertex $1$, Vertex $2$, $\ldots$, Vertex $N$. For each pair of integers such that 阅读全文
posted @ 2023-01-02 20:24
灰鲭鲨
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Problem StatementYou are given an undirected tree with $N$ vertices. Let us call the vertices Vertex $1$, Vertex $2$, $\ldots$, Vertex $N$. For each $ 阅读全文
posted @ 2023-01-02 19:59
灰鲭鲨
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杜教筛是拿来求积性函数前缀和的东西 $h=fg$ $s(n)=\sum\limits_{i=1}^ng(i)$ 而杜教筛可以在 $O(n^{\frac 23})$ 的复杂度内求出 $s(n)$，前提是存在两个很好求前缀和的函数 $f$ 和 $h$ 满足 $h=fg$ $\sum\limits_{i= 阅读全文
posted @ 2023-01-02 18:44
灰鲭鲨
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Problem StatementTakahashi has $A$ apple seedlings, $B$ banana seedlings, and $C$ cherry seedlings. Seedlings of the same kind cannot be distinguished 阅读全文
posted @ 2023-01-02 17:25
灰鲭鲨
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