//
// demonstrates a vector of vectors
// allocates a vector of vectors, and for each element in the vector, allocates a vector of integers
//
//
// Written by Maxwell Sayles, 2001, for CPSC331, University of Calgary.
//

#include <iostream>
#include <iomanip>
using namespace std;

//
// demonstrates a vector of vectors
// 'data' is a vector of vectors
// for each element in data, we allocate another vector of integers
//
class Matrix
{
public:
	Matrix (int rows, int columns);
	~Matrix();
	
	int getRowCount()			{ return this->rows; }
	int getColumnCount()		{ return this->columns; }
	
	int getItem (int row, int column);
	void setItem (int row, int column, int value);
	
private:
	int** data;
	int rows;
	int columns;
};

//
// construct the matrix
// allocate a vector of vectors to integers
// for each element in the vector, allocate another vector of integers
//
Matrix::Matrix (int rows, int columns)
{
	this->rows = rows;
	this->columns = columns;
	this->data = new int*[rows]; // allocate vector of vectors (meaning, allocate an array of pointers, so a pointer to pointers)
	for (int i = 0;  i < rows;  i = i + 1)
	{	// for each element in above, allocate a vector integers
		this->data[i] = new int[columns];
	}
}

// 
// destruct
// delete each vector integers
// then delete the vector of vectors
//
Matrix::~Matrix()
{
	for (int i = 0;  i < this->rows;  i = i + 1)
	{
		delete[] this->data[i];
	}
	delete[] this->data;
}


//
// retrieve an item from the matrix
//
int Matrix::getItem (int row, int column)
{
	int* columnVector = this->data[row];
	return columnVector[column];
	// can be shortened to
	// return this->data[row][column];
}


//
// set an item in the matrix
//
void Matrix::setItem (int row, int column, int value)
{
	int* columnVector = this->data[row];
	columnVector[column] = value;
	// can be shortened to
	// this->data[row][column] = value;
}


//
// program entry
//
int main()
{
	// construct a matrix
	Matrix m (16, 18);
	
	int c = 0;
	int r = 0;
	
	// fill out matrix with multiplication table
	for (c = 0;  c < m.getColumnCount();  c = c + 1)
	{
		for (r = 0;  r < m.getRowCount();  r = r + 1)
		{
			m.setItem (r, c, c*r);
		}
	}
	
	// print indexes along columns
	cout << " x ";
	for (c = 0;  c < m.getColumnCount();  c = c + 1)
	{
		// similar to cout, only this will print decimal values right aligned to four digits
		cout << setw(3) << c << ' ';
	}
	cout << endl << endl;
	
	// print matrix
	for (r = 0;  r < m.getRowCount();  r = r + 1)
	{
		cout << setw(2) << r << ' ';
		for (c = 0;  c < m.getColumnCount();  c = c + 1)
		{
			int value = m.getItem (r, c);
			cout << setw(3) << value << ' ';
		}
		cout << endl;
	}
		
	cout << endl;
		
	return 0;
}