Can I get help with implementation in java

#classs 8puzzle.java

package project;

import java.io.FileNotFoundException;

public class EightPuzzle

{

/**

* This static method solves an 8-puzzle with a given initial state using three heuristics. The

* first two, allowing single moves only, compare the board configuration with the goal configuration

* by the number of mismatched tiles, and by the Manhattan distance, respectively. The third

* heuristic, designed by yourself, allows double moves and must be also admissible. The goal

* configuration set for all puzzles is

*

* 1 2 3

* 8 4

* 7 6 5

*

* @param s0

* @return a string specified in the javadoc below

*/

public static String solve8Puzzle(State s0)

{

// TODO

// 1) Return a message that starts with "No solution exists for the following initial

// state:" and follows with a blank line and then what would be the output from a

// call s0.toString(). See the end of Section 6 in the project description for an

// example.

// 2) Otherwise, solve the puzzle with the three heuristics. The two solutions generated by

// the first two heuristics may be different but must have the same length for optimality.

Heuristic h[] = {Heuristic.TileMismatch, Heuristic.ManhattanDist, Heuristic.DoubleMoveHeuristic };

String [] moves = new String[3];

for (int i = 0; i < 3; i++)

{

moves[i] = AStar(s0, h[i]);

}

// 3) Combine the three solution strings into one that would print out in the

// output format specified in Section 6 of the project description.

return null;

}

/**

* This method implements the A* algorithm to solve the 8-puzzle with an input initial state s0.

* The algorithm implementation is described in Section 3 of the project description.

*

* Precondition: the puzzle is solvable with the initial state s0.

*

* @param s0 initial state

* @param h heuristic

* @return solution string

*/

public static String AStar(State s0, Heuristic h)

{

// TODO

// Initialize the two lists used by the algorithm.

OrderedStateList OPEN = new OrderedStateList(h, true);

OrderedStateList CLOSE = new OrderedStateList(h, false);

// Implement the algorithm described in Section 3 to solve the puzzle.

// Once a goal state s is reached, call solutionPath(s) and return the solution string.

return null;

}

/**

* From a goal state, follow the predecessor link to trace all the way back to the initial state.

* Meanwhile, generate a string to represent board configurations in the reverse order, with

* the initial configuration appearing first. Between every two consecutive configurations

* is the move that causes their transition. A blank line separates a move and a configuration.

* In the string, the sequence is preceded by the total number of moves and a blank line.

*

* See Section 6 in the projection description for an example.

*

* Call the toString() method of the State class.

*

* @param goal

* @return

*/

private static String solutionPath(State goal)

{

// TODO

return null;

}

}