Difference Matrix

You are given an integer $N$. You need to find an $N\times N$ matrix such that: - Each element of the matrix is an integer from $1$ to $N^2$; - All elements of the matrix are **unique**; - The absolute difference between elements in neighbouring cells is **strictly greater** than $1$. It can be shown that there is at least one matrix that satisfies the given conditions. If multiple matrices satis