AtCoder Grand Contest 046
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Problem Statement
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We have a grid with $A$ horizontal rows and $B$ vertical columns, with the squares painted white. On this grid, we will repeatedly apply the following operation:
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- Assume that the grid currently has
$a$horizontal rows and$b$vertical columns. Choose "vertical" or "horizontal". - If we choose "vertical", insert one row at the top of the grid, resulting in an
$(a+1) \times b$grid.- If we choose "horizontal", insert one column at the right end of the grid, resulting in an
$a \times (b+1)$grid.
- If we choose "horizontal", insert one column at the right end of the grid, resulting in an
- Then, paint one of the added squares black, and the other squares white.
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Assume the grid eventually has $C$ horizontal rows and $D$ vertical columns. Find the number of ways in which the squares can be painted in the end, modulo $998244353$.
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Constraints
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$1 \leq A \leq C \leq 3000$$1 \leq B \leq D \leq 3000$$A$,$B$,$C$, and$D$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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A B C D
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Output
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Print the number of ways in which the squares can be painted in the end, modulo $998244353$.
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样例
Input #1
1 1 2 2
Output #1
3
Any two of the three squares other than the bottom-left square can be painted black.
Input #2
2 1 3 4
Output #2
65
Input #3
31 41 59 265
Output #3
387222020
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。