AtCoder Regular Contest 199 (Div. 1)
C
Circular Tree Embedding
AtCoder
⌀ 3111
原题
← BD →
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Problem Statement

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In this problem, we simply call a tree with $N$ vertices numbered $1,2,\ldots,N$ and unnumbered edges an $N$-vertex tree.

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When an $N$-vertex tree $T$ and a permutation $Q=(Q_1,Q_2,\ldots,Q_N)$ of $(1,2,\ldots,N)$ satisfy the following condition, the permutation $Q$ is called a good permutation of tree $T$:

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There are $N$ points $1,2,\ldots,N$ arranged counterclockwise at equal intervals on a circle in this order. For each edge $\lbrace u,v\rbrace$ of tree $T$, draw a line segment connecting the two points $Q_u,Q_v$. Then, among the $N-1$ line segments drawn, no two of them have a common point except at their endpoints.

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You are given $M$ permutations of $(1,2,\ldots,N)$: $P^1=(P^1_1,P^1_2,\ldots,P^1_N),P^2=(P^2_1,P^2_2,\ldots,P^2_N),\ldots,P^M=(P^M_1,P^M_2,\ldots,P^M_N)$.

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Find the number, modulo $998244353$, of $N$-vertex trees such that $P^1,P^2,\ldots,P^M$ are all good permutations.

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Constraints

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  • $2\leq N,M\leq 500$
  • $P^1,P^2,\ldots,P^M$ are permutations of $(1,2,\ldots,N)$.
  • All input values are integers.
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Input

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The input is given from Standard Input in the following format:

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N M
P^1_1 P^1_2 \ldots P^1_N
P^2_1 P^2_2 \ldots P^2_N
\vdots
P^M_1 P^M_2 \ldots P^M_N

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Output

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Output the number, modulo $998244353$, of $N$-vertex trees such that $P^1,P^2,\ldots,P^M$ are all good permutations.

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样例

Input #1
4 2
1 4 2 3
3 1 4 2
Output #1
8
For example, for the following two trees, both $P^1,P^2$ are good permutations. (The blue numbers represent vertex numbers.) ![image](https://img.atcoder.jp/arc199/9f18f81fa8fb939d65e4d941450a2dbf.png) On the other hand, for the following tree, $P^2$ is not a good permutation. ![image](https://img.atcoder.jp/arc199/6b602382a1f4bc4e7d6f792c0b2f7d20.png) There are $8$ four-vertex trees in total such that both $P^1,P^2$ are good permutations.
Input #2
12 3
7 9 1 10 8 12 2 6 11 5 4 3
8 10 4 12 11 7 6 3 1 2 9 5
10 4 9 7 5 1 3 11 8 12 6 2
Output #2
540
题目信息
题号
arc199_c
时间限制
2 s
内存限制
1024 MB

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