Difference Matrix.cpp

#ifdef DEBUG
#include "debug.h"
#endif // DEBUG
#ifndef DEBUG
template <typename T>
void debug(T &x){}
template <typename T>
void debug(T &x, int i, int j){}
#endif // DEBUG

#include <bits/stdc++.h>

using namespace std;

int main(){
    cin.tie(nullptr), ios::sync_with_stdio(false);
    int T;
    cin >> T;
    while(T--){
        int N;
        cin >> N;
        if(N == 4){
            cout << "12 10 6 14\n3 8 4 1\n5 15 11 9\n2 7 13 16\n";
        }else{
            vector <int> v;
            for(int i = 1; i <= N; i+= 2) v.push_back(i);
            for(int i = 2; i <= N; i+= 2) v.push_back(i);
            for(int r = 0; r < N; r++){
                for(int i : v) cout << (i + r * N) << " ";
                cout << "\n";
            }
        }
    }
}