Class Board

LabEnv/04Lab/Board.java:13–169

import java.util.Arrays;

public class Board {
    private static final int[][] DIR = { { 0, 1 }, { 0, -1 }, { 1, 0 }, { -1, 0 } };
    private final int n;
    private final int[][] tiles;
    private final int hammingD;
    private final int manhattanD;
    private final int emptyPosX;
    private final int emptyPosY;

    // create a board from an n-by-n array of tiles,
    // where tiles[row][col] = tile at (row, col)
    public Board(int[][] tiles) {
        if (tiles == null) throw new IllegalArgumentException();
        this.tiles = new int[tiles.length][tiles[0].length];
        for (int i = 0; i < tiles.length; i++)
            this.tiles[i] = Arrays.copyOf(tiles[i], tiles.length);
        n = tiles.length;
        // calculate hamming distance and manhattan distance
        int h = 0, m = 0, px = 0, py = 0;
        for (int i = 0; i < n; i++) {
            for (int j = 0; j < n; j++) {
                if (tiles[i][j] == 0) {
                    px = i;
                    py = j;
                    continue;
                }
                // if the tile is in the right position i * n + j + 1 = val
                int val = tiles[i][j] - 1;
                int man = Math.abs(val / n - i) + Math.abs(val % n - j);
                if (man > 0) h++;
                m += man;
            }
        }
        manhattanD = m;
        hammingD = h;
        emptyPosX = px;
        emptyPosY = py;
    }

    // string representation of this board
    public String toString() {
        StringBuilder s = new StringBuilder();
        s.append(n + "\n");
        for (int i = 0; i < n; i++) {
            for (int j = 0; j < n; j++) {
                s.append(String.format("%2d ", tiles[i][j]));
            }
            s.append("\n");
        }
        return s.toString();
    }

    // board dimension n
    public int dimension() {
        return n;
    }

    // number of tiles out of place