/**
 * The interface <code>SudokuMatrix</code> provides the information for
 * an instance of the puzzle.
 * 
 * @author Lucia Moura
 *
 */

public interface SudokuMatrix {
	
	/**
	 * @param i is a row index 
	 * @param j is a column index
	 * @return "given" at position i,j of the Sudoku puzzle or -1 if it is an empty cell
	 */
	public int getPuzzle(int i, int j);
	
	/**
	 * @param i is a row index
	 * @param j is a column index
	 * @return true if position i,j contains a "given" and false otherwise
	 */
	public boolean isGiven(int i, int j);

	/**
	 * @param i is a row index 
	 * @param j is a column index
	 * @return the number that must be at position i,j in the Sudoku puzzle final solution
	 */
	public int getSolution(int i, int j);
}