201492: [AtCoder]ARC149 C - Avoid Prime Sum
Description
Score : $500$ points
Problem Statement
You are given a positive integer $N$.
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.
- 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.
Under the Constraints of this problem, it can be proved that such a way to fill the grid always exists.
Constraints
- $3\leq N\leq 1000$
Input
The input is given from Standard Input in the following format:
$N$
Output
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:
$A_{11}$ $\ldots$ $A_{1N}$ $\vdots$ $A_{N1}$ $\ldots$ $A_{NN}$
If there are multiple ways to fill the grid under the conditions, any of them will be accepted.
Sample Input 1
4
Sample 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.