AtCoder Grand Contest 052
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Problem Statement
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You are given a prime number $P$, which you don't like.
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Let's call an array of integers $A_1, A_2, \dots, A_N$ good, if it is possible to reorder the elements in such a way that no prefix sum is divisible by $P$ (that is, there is no $i$ with $1 \le i \le N$ and $A_1 + A_2 + \dots + A_i \equiv 0 \bmod P$ after the reordering).
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Consider all $(P-1)^N$ arrays of length $N$ with elements from $1$ to $P-1$. How many of them are good?
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As this number can be very big, output it modulo $998244353$.
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Constraints
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$1 \le N \le 5000$$2 \le P \le 10^8$$P$is a prime.
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Input
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Input is given from Standard Input in the following format:
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N P
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Output
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Output the number of good arrays modulo $998244353$.
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样例
Input #1
2 5
Output #1
12
There are $12$ good arrays: $[1, 1]$, $[1, 2]$, $[1, 3]$, $[2, 1]$, $[2, 2]$, $[2, 4]$, $[3, 1]$, $[3, 3]$, $[3, 4]$, $[4, 2]$, $[4, 3]$, $[4, 4]$.
Input #2
4 3
Output #2
8
There are $8$ good arrays: $[1, 1, 1, 2]$, $[1, 1, 2, 1]$, $[1, 2, 1, 1]$, $[2, 1, 1, 1]$, $[2, 2, 2, 1$], $[2, 2, 1, 2]$, $[2, 1, 2, 2]$, $[1, 2, 2, 2]$.
Input #3
5000 99999989
Output #3
51699346
Input #4
2021 307
Output #4
644635349
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。