AtCoder Regular Contest 163
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Problem Statement
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Consider a directed graph $G$ with $N$ vertices numbered $1$ to $N$ that satisfies all of the following conditions.
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$G$is a tournament. In other words,$G$has no multi-edges or self-loops, and for any two vertices$u,v$of$G$, exactly one of the edges$u \rightarrow v$and$v \rightarrow u$exists.- Among the edges of
$G$, exactly$M$are directed from a vertex with a smaller number to a vertex with a larger number.
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Find the total number of strongly connected components over all such directed graphs $G$, modulo $998244353$.
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Constraints
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$1 \le N \le 30$$0 \le M \le \frac{N(N-1)}{2}$
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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
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Output
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Print the answer.
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样例
Input #1
3 1
Output #1
7
Below are the three directed graphs $G$ that satisfy the conditions. The numbers of their strongly connected components are $3,1,3$ from left to right, so the answer is $7$.

Input #2
6 2
Output #2
300
Input #3
25 156
Output #3
902739687
题目信息
题面与样例版权归 AtCoder 及出题人所有;中文翻译由 AI 生成(CI 管线),如有出入请以原文为准。