Board.java

import java.util.Arrays;

public class Board implements Comparable<Board>{
  private static int[] goal;
  private int g;
  private int value;
  private int[] state;
  private int posZ;
  private Board parent;
  private String hash;

  public Board(int state[], int g, int posZ, Board parent){
		this.g = g;
		this.state = state;
		this.posZ = posZ;
		value = this.getH() + g;
		this.parent = parent;
		hash = generateHash(state);
	}
  public Board(int state[], int g){
    this.g = g;
    this.state = state;
    this.posZ = this.getPosZ(state);
    value = this.getH() + g;
		hash = generateHash(state);
  }	
  public Board(Board b, Board parent){
    this.g = b.getG();
    this.state = b.getState();
    this.posZ = this.getPosZ(state);
    value = this.getH() + g;
    this.parent = parent;
		hash = generateHash(state);
  }
	
  private int getH(){
    int count = 0;
	  
    for(int i = 0; i < state.length; i++){
      if(state[i] != goal[i]){
        count++;
      }
    }
    return count;
  }
private int getPosZ(int[] arr){
    for(int i = 0; i < arr.length; i++){
      if(arr[i] == 0) return i;
    }
    return -1;
  }

  public boolean equals(int[] check){
    return Arrays.equals(state, check);
  }

  @Override
  public int compareTo(Board board){
    return this.getVal() - board.getVal();
  }

  public String toString(){
    String res = "";
    for(int i = 0; i < state.length; i++){
			if(state[i] != -1){
				if(state[i] > 9){
					res += state[i] + " ";
				}else {
					res += state[i] + "  ";
				}
			} else {
				res += "\n";
			}
  }
	  return res;
  }

  public int getVal(){
    return value;
  }

  public int getZ(){
    return posZ;
  }

  public int getG(){
    return g;
  }

  public int[] getState(){
    return Arrays.copyOf(state, state.length);
  }
		
	public String getHash(){
		return hash;
	}
	
  public Board getParent(){
    return parent;
  }
	public static int[] getGoal(){
		return goal;
	}

	public static void setGoal(int[] inGoal){
		goal = inGoal;
	}
		
	public static String generateHash(int state[]){
		String output = "";
		int r = 1;
		int c = 1;
		for(int i = 0; i < state.length; i++){
			int curState = state[i];
			if(curState != -1) {
				int n = (r + c)*curState;
				output += n;
			}else{
				r++;
			}
		}
		return output;
	}
}