ユニークビジョンプログラミングコンテスト2022(AtCoder Beginner Contest 248)
G
GCD cost on the tree
AtCoder
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原题
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Problem Statement

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You are given an undirected tree with $N$ vertices. Let us call the vertices Vertex $1$, Vertex $2$, $\ldots$, Vertex $N$. For each $1\leq i\leq N-1$, the $i$-th edge connects Vertex $U_i$ and Vertex $V_i$. Additionally, each vertex is assigned a positive integer: Vertex $i$ is assigned $A_i$.

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The cost between two distinct vertices $s$ and $t$, $C(s,t)$, is defined as follows.

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Let $p_1(=s)$, $p_2$, $\ldots$, $p_k(=t)$ be the vertices of the simple path connecting Vertex $s$ and Vertex $t$, where $k$ is the number of vertices in the path (including the endpoints). Then, let $C(s,t)=k\times \gcd (A_{p_1},A_{p_2},\ldots,A_{p_k})$, where $\gcd (X_1,X_2,\ldots, X_k)$ denotes the greatest common divisor of $X_1,X_2,\ldots, X_k$.

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Find $\displaystyle\sum_{i=1}^{N-1}\sum_{j=i+1}^N C(i,j)$, modulo $998244353$.

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Constraints

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  • $2 \leq N \leq 10^5$
  • $1 \leq A_i\leq 10^5$
  • $1\leq U_i<V_i\leq N$
  • All values in input are integers.
  • The given graph is a tree.
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Input

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Input is given from Standard Input in the following format:

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N
A_1 A_2 \cdots A_N
U_1 V_1
U_2 V_2
\vdots
U_{N-1} V_{N-1}

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Output

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Print $\displaystyle\sum_{i=1}^{N-1}\sum_{j=i+1}^N C(i,j)$, modulo $998244353$.

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样例

Input #1
4
24 30 28 7
1 2
1 3
3 4
Output #1
47
There are edges directly connecting Vertex $1$ and $2$, Vertex $1$ and $3$, and Vertex $3$ and $4$. Thus, the costs are computed as follows. - $C(1,2)=2\times \gcd(24,30)=12$ - $C(1,3)=2\times \gcd(24,28)=8$ - $C(1,4)=3\times \gcd(24,28,7)=3$ - $C(2,3)=3\times \gcd(30,24,28)=6$ - $C(2,4)=4\times \gcd(30,24,28,7)=4$ - $C(3,4)=2\times \gcd(28,7)=14$ Thus, the sought value is $\displaystyle\sum_{i=1}^{3}\sum_{j=i+1}^4 C(i,j)=(12+8+3)+(6+4)+14=47$ modulo $998244353$, which is $47$.
Input #2
10
180 168 120 144 192 200 198 160 156 150
1 2
2 3
2 4
2 5
5 6
4 7
7 8
7 9
9 10
Output #2
1184
题目信息

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