P1549 [NOIP 1997 Senior] Chessboard Problem
Background
NOIP 1997 Senior, Problem 1.
[P5512](https://www.luogu.com.cn/problem/P5512) is the enhanced testdata version of this problem.
The actual constraints for this problem are $1\le N\le 5$. There is no guarantee that a solution without hardcoding can pass the original constraints.
Description
On an $N \times N$ ($1 \le N \le 10$) board, fill in the $N ^ 2$ numbers $1, 2, \dots, N ^ 2$, so that the sum of any two adjacent numbers is a prime number.
For example, when $N = 2$, there is:
| $1$ | $2$ |
| :-----------: | :-----------: |
| $4$ | $3$ |
The adjacent pairs whose sums are prime are:
$1+2,1+4,4+3,2+3$
When $N=4$, one possible arrangement is:
| $1$ | $2$ | $11$ | $12$ |
| :-----------: | :-----------: | :-----------: | :-----------: |
| $16$ | $15$ | $8$ | $5$ |
| $13$ | $4$ | $9$ | $14$ |
| $6$ | $7$ | $10$ | $3$ |
Here we stipulate that the top-left cell must contain the number $1$.
Input Format
A single integer $N$.
Output Format
If multiple solutions exist, output the arrangement whose sum of the first row and the first column is minimal. Output the board in $N$ lines, each containing $N$ integers separated by single spaces. If no solution exists, output `NO`.
Explanation/Hint
Translated by ChatGPT 5