AtCoder Beginner Contest 276
G
Count Sequences
AtCoder
⌀ 2278
原题
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翻译中…

Problem Statement

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Find the number of sequences of integers with $N$ terms, $A=(a_1,a_2,\ldots,a_N)$, that satisfy the following conditions, modulo $998244353$.

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  • $0 \leq a_1 \leq a_2 \leq \ldots \leq a_N \leq M$.
  • For each $i=1,2,\ldots,N-1$, the remainder when $a_i$ is divided by $3$ is different from the remainder when $a_{i+1}$ is divided by $3$.
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Constraints

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  • $2 \leq N \leq 10^7$
  • $1 \leq M \leq 10^7$
  • All values in the input 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

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Output

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Print the answer.

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样例

Input #1
3 4
Output #1
8
Here are the eight sequences that satisfy the conditions. - $(0,1,2)$ - $(0,1,3)$ - $(0,2,3)$ - $(0,2,4)$ - $(1,2,3)$ - $(1,2,4)$ - $(1,3,4)$ - $(2,3,4)$
Input #2
276 10000000
Output #2
909213205
Be sure to find the count modulo $998244353$.
题目信息
题号
abc276_g
时间限制
4 s
内存限制
1024 MB

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。