1868A - Fill in the Matrix - CodeForces Solution

// Source: https://usaco.guide/general/io
 
#include <bits/stdc++.h>
using namespace std;
#define int long long
int mex(vector<int> &arr, int N)
{
 
  // sort the array
  sort(arr.begin(), arr.end());
 
  int mex = 0;
  for (int idx = 0; idx < N; idx++)
  {
    if (arr[idx] == mex)
    {
      // Increment mex
      mex += 1;
    }
  }
 
  // Return mex as answer
  return mex;
}
 
int calcbeaut(vector<vector<int>> arr, int coloms, int rows){
	vector<int> mexv;
	for (int i=0; i < coloms; i++){
		vector<int> v;
		for (int j = 0; j < rows; j++){
			v.push_back(arr[j][i]);
		}
		mexv.push_back(mex(v, v.size()));
	}
	for (int i = 0; i < mexv.size(); i++){
		//cout << mexv[i] << "\n";
	}
	return mex(mexv, mexv.size());
}
 
signed main() {
	int t;
	cin >> t;
	while (t--){
		int n,m;
		cin >> n >> m;
		int dupn = n;
		n = min(n,m);
		vector<vector<int>> ans;
		ans.push_back({});
 
		for (int i = 0; i< dupn; i++){
			ans.push_back({});
			for (int j = 0; j < m; j++){
				ans[i].push_back(0);
			}
		}
		m-=1;
		// for (int i  =0; i < n; i++){
		// 	ans[i][0] = m-1;
		// }
		int awf, bawf;
		vector<vector<int>> aww;
		awf = -1;
		bawf = -1;
		for (int i = 0; i < n; i++){
			for (int j = i; j < m; j++){
				ans[i][j] = j-i;
			}
		}
		if (m>4){
			if (true){
			for (int i = 1; i < n; i++){
				for (int j = i-1; j >=0; j--){
					ans[i][j] = m-(m-(m-(j)-1)-1)-1;
					if (ans[i][j] == j+1){
						ans[i][j] += 1;
						//ans[i][j-1] = 10;
						awf = i;
						bawf = j-1;
						aww.push_back({awf,bawf});
					}
				}
			}}
			else{
				for (int i = 1; i < n; i++){
				for (int j = i-1; j >=0; j--){
					ans[i][j] = (m-(m-(j)-1)-1);
				}
				//
			}
			}
				for (int i =0; i < n; i++){
					ans[i][ans[i].size()-1] = ans[i].size()-1;
				}
			for (int i = 1; i < n; i++){
				//ans[i][0] = m-1;
			}
			int ababb = 0;
			if (n > 2){
				//ans[n-1][m-1] = 0;
			}
		}
		else if (m == 4){
			vector<vector<int>> answer = {
				{0, 1, 2, 3, 4},
				{3, 0, 1, 2, 4},
				{2, 3, 0, 1, 4},
				{2, 3, 1, 0, 4},
				{2, 3, 1, 0, 4},
			};
			n = 5;
			for (int i = 0; i < min(dupn,n); i++){
				ans[i] = answer[i];
			}
		}
		else if (m == 3){
			vector<vector<int>> answer = {
				{0, 1, 2, 3},
				{2, 0, 1, 3},
				{2, 1, 0, 3},
				{2, 1, 0, 3},
			};
			n = 4;
			for (int i = 0; i < min(dupn,n); i++){
				ans[i] = answer[i];
			}
		}
		else if (m == 2){
			vector<vector<int>> answer = {
				{1,0,2},
				{0,2,1}
			};
			n = 2;
			ans[0] = answer[0];
			ans[1] = answer[1];
			for (int i =0; i < min(dupn,n); i++){
				ans[i] = answer[i];
			}
		}
		else if (m == 1){
			vector<vector<int>> answer = {
				{0, 1}
			};
			n = 1;
			ans[0] = answer[0];
		}
		else{
			vector<vector<int>> answer = {
				{0}
			};
			n = 1;
			ans[0] = answer[0];
		}
 
		vector<int> model = ans[0];
		for (int i = n; i < dupn; i++){
			ans[i] = model;
		}
		for (int i = 0; i < aww.size(); i++){
			ans[aww[i][0]][aww[i][1]] -= 1;
		}
		//cout << n+1 << "\n";
		//cout << "\n";
		cout << calcbeaut(ans, ans[0].size(), ans.size()-1) << "\n";
		for (int i = 0; i < dupn; i++){
			for (int j = 0; j < ans[i].size(); j++){
				cout << ans[i][j] << " ";
			}
			cout << "\n";
		}
	}
}