AtCoder Regular Contest 149
C
Avoid Prime Sum
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⌀ 1415
原题
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Problem Statement

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You are given a positive integer $N$.

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Fill each square of a grid with $N$ rows and $N$ columns by writing a positive integer not greater than $N^2$ so that all of the following conditions are satisfied.

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  • Two positive integers written in horizontally or vertically adjacent squares never sum to a prime number.
  • Every positive integer not greater than $N^2$ is written in one of the squares.
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Under the Constraints of this problem, it can be proved that such a way to fill the grid always exists.

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Constraints

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  • $3\leq N\leq 1000$
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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

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Output

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Print a way to fill the grid under the conditions in the following format, where $A_{ij}$ is the positive integer at the $i$-th row and $j$-th column:

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A_{11} \ldots A_{1N}
\vdots
A_{N1} \ldots A_{NN}

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If there are multiple ways to fill the grid under the conditions, any of them will be accepted.

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样例

Input #1
4
Output #1
15 11 16 12
13 3 6 9
14 7 8 1
4 2 10 5
In this grid, every positive integer from $1$ through $16$ is written once. Additionally, among the sums of two positive integers written in horizontally or vertically adjacent squares are $15+11=26$, $11+16=27$, and $15+13=28$, none of which is a prime number.
题目信息
题号
arc149_c
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。