1520C - Not Adjacent Matrix.cpp

/*
We will consider the numbers a and b as adjacent if they differ by exactly one, that is, |a-b|=1.

We will consider cells of a square matrix n×n as adjacent if they have a common side, that is, for cell (r,c) cells (r,c-1), (r,c+1), (r-1,c) and (r+1,c) are adjacent to it.

For a given number n, construct a square matrix n×n such that:

Each integer from 1 to n2 occurs in this matrix exactly once;
If (r1,c1) and (r2,c2) are adjacent cells, then the numbers written in them must not be adjacent.
Input
The first line contains one integer t (1=t=100). Then t test cases follow.

Each test case is characterized by one integer n (1=n=100).

Output
For each test case, output:

-1, if the required matrix does not exist;
the required matrix, otherwise (any such matrix if many of them exist).
The matrix should be outputted as n lines, where each line contains n integers.

Example
inputCopy
3
1
2
3
outputCopy
1
-1
2 9 7
4 6 3
1 8 5
*/




#include<bits/stdc++.h>
using namespace std;
 
int main(){
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    
    int t;
    cin >> t;
    
    while (t--) {
    	int n;
    	cin >> n;
    	
    	if (n == 1) cout << 1;
    	else if (n == 2) cout << -1;
    	else {
    		int num = 1;
    		for (int i = 0; i < n; i++) {
    			for (int j = 0; j < n; j++) {
    				if (num > n * n) num = 2;
    				cout << num << " ";
    				num += 2;
    				
				}
				cout << endl;
			}
		}
    	cout << endl;
	}
  	
    return 0;
}