AtCoder Beginner Contest 276
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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。