#include <iostream>                                               // CSS 332
using namespace std;

void fill(int **&, int);
void print(int **&, int);
void cleanup(int **&, int);

int main() {
    int **A;             //double pointer used to store dynamic grid
    A = new int *[3];    //dynamically allocate an array of pointers for rows

    // could use for loop 
    A[0] = new int[3];   //allocate 1st row dynamically
    A[1] = new int[3];   //allocate 2nd row dynamically
    A[2] = new int[3];   //allocate 3rd row dynamically

    fill(A, 3);
    print(A, 3);
    cleanup(A, 3);
    return 0;
}

//----------------------------------- fill ----------------------------------
// fill array with appropriate values
// Because arrays are refs following also works:    void fill(int **A, int n)

void fill(int **&A, int n) {
   for (int i = 0; i < n; i++) {
      for (int j = 0; j < n; j++) {
         A[i][j] =  i - j;
      }
   }
}

//-------------------------------- print ------------------------------------
// traverse by row, then column

void print(int **&A, int n) {
   for (int i = 0; i < n; i++) {
      for (int j = 0; j < n; j++) {
         cout << A[i][j] << "  " ;
      }
      cout << endl;
   }
}

//--------------------------------- cleanup ---------------------------------
// delete all memory allocated
// Because arrays are refs following also works:  void cleanup(int **A, int n)

void cleanup(int **&A, int n) {
   for (int i = 0; i < n; i++) {
       delete [] A[i];             //dynamically deallocate each row 
       A[i] = NULL;
   }
   delete [] A;                    //dynamically deallocate array of pointers 
   A = NULL;
}