View source for Computer Science/61b/Homework/hw6/SimpleBoard.java

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 /* SimpleBoard.java */
 
 /**
 *  Simple class that implements an 8x8 game board with three possible values
  *  for each cell:  0, 1 or 2.
  *
  *  DO NOT CHANGE ANY PROTOTYPES IN THIS FILE.
  **/
 
 public class SimpleBoard {
 	private final static int DIMENSION = 8;
 	private int[][] grid;
 	
 	/**
 		*  Invariants:  
 	 *  (1) grid.length == DIMENSION.
 	 *  (2) for all 0 <= i < DIMENSION, grid[i].length == DIMENSION.
 	 *  (3) for all 0 <= i, j < DIMENSION, grid[i][j] >= 0 and grid[i][j] <= 2.
 	 **/
 	
 	/**
 		*  Construct a new board in which all cells are zero.
 	 */
 	
 	public SimpleBoard() {
 		grid = new int[DIMENSION][DIMENSION];
 	}
 	
 	/**
 		*  Set the cell (x, y) in the board to the given value mod 3.
 	 *  @param value to which the element should be set (normally 0, 1, or 2).
 	 *  @param x is the x-index.
 	 *  @param y is the y-index.
 	 *  @exception ArrayIndexOutOfBoundsException is thrown if an invalid index
 	 *  is given.
 	 **/
 	
 	public void setElementAt(int x, int y, int value) {
 		grid[x][y] = value % 3;
 		if (grid[x][y] < 0) {
 			grid[x][y] = grid[x][y] + 3;
 		}
 	}
 	
 	/**
 		*  Get the valued stored in cell (x, y).
 	 *  @param x is the x-index.
 	 *  @param y is the y-index.
 	 *  @return the stored value (between 0 and 2).
 	 *  @exception ArrayIndexOutOfBoundsException is thrown if an invalid index
 	 *  is given.
 	 */
 	
 	public int elementAt(int x, int y) {
 		return grid[x][y];
 	}
 	
 	/**
 		*  Returns true if "this" SimpleBoard and "board" have identical values in
 	 *    every cell.
 	 *  @param board is the second SimpleBoard.
 	 *  @return true if the boards are equal, false otherwise.
 	 */
 	
 	public boolean equals(Object board) {
 		if (board.getClass() == this.getClass()) {
 			return (this.hashCode() == board.hashCode());
 		} else {
 			return false;
 		}
 	}
 	
 	/**
 		*  Returns a hash code for this SimpleBoard.
 	 *  @return a number between Integer.MIN_VALUE and Integer.MAX_VALUE.
 	 */
 	
 	public int hashCode() {
 		int hash = 0;
 		for (int io=0; io<DIMENSION; io++) {
 			for (int ii=0; ii<DIMENSION; ii++) {
 				hash = hash * 3 + grid[io][ii];
 			}
 		}
 		return hash;
 	}
 }