AtCoder Regular Contest 107
D
Number of Multisets
AtCoder
⌀ 2099
原题
← CE →
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Problem Statement

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You are given two positive integers $N$ and $K$. How many multisets of rational numbers satisfy all of the following conditions?

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  • The multiset has exactly $N$ elements and the sum of them is equal to $K$.
  • Each element of the multiset is one of $1, \frac{1}{2}, \frac{1}{4}, \frac{1}{8}, \dots$. In other words, each element can be represented as $\frac{1}{2^i}\ (i = 0,1,\dots)$.
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The answer may be large, so print it modulo $998244353$.

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Constraints

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  • $1 \leq K \leq N \leq 3000$
  • All values in input are integers.
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Input

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Input is given from Standard Input in the following format:

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N K

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Output

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Print the number of multisets of rational numbers that satisfy all of the given conditions modulo $998244353$.

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样例

Input #1
4 2
Output #1
2
The following two multisets satisfy all of the given conditions: - ${1, \frac{1}{2}, \frac{1}{4}, \frac{1}{4}}$ - ${\frac{1}{2}, \frac{1}{2}, \frac{1}{2}, \frac{1}{2}}$
Input #2
2525 425
Output #2
687232272
题目信息
题号
arc107_d
时间限制
2 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。