32. Find INDEX in dual array C++

#include <iostream>
#include <vector>

int main()
{
    using namespace std;

    int num_to_find;
    cin >> num_to_find;

    int row_number, col_number;
    cin >> row_number >> col_number;

    vector<vector<int>> matrix;
    for (int row = 0; row < row_number; ++row)
    {
        vector<int> matrix_row;
        for (int col = 0; col < col_number; ++col)
        {
            int n;
            cin >> n;
            matrix_row.push_back(n);
        }
        matrix.push_back(matrix_row);
    }

    bool found = false;
    for (int row = 0; row < row_number; ++row)
        for (int col = 0; col < col_number; ++col)
            if (matrix[row][col] == num_to_find)
            {
                cout << row << col << endl;
                found = true;
            }

    if (!found)
        cout << "Number not found\n";

    return 0;
}

//#include <iostream>
//#include <vector>
//int main()
//{
//  using namespace std;
//
//  int num_to_find;
//  cin >> num_to_find;
//
//  int rows, cols;
//  cin >> rows >> cols;
//
//  vector<int> matrix;
//  for (int i = 0; i < rows * cols; ++i)
//  {
//      int n;
//      cin >> n;
//      matrix.push_back(n);
//  }
//
//  bool found = false;
//  for (int i = 0; i < matrix.size(); ++i)
//      if (matrix[i] == num_to_find)
//      {
//          int row = i / cols, col = i % cols;
//          cout << row << col << endl;
//          found = true;
//      }
//
//  if (!found)
//      cout << "Number not found\n";
//
//  return 0;
//}