a*算法实现八数码问题java代码

以下是A*算法实现八数码问题的Java代码：

import java.util.*;

public class EightPuzzleSolver {
    private static final int[][] GOAL = {{1, 2, 3}, {8, 0, 4}, {7, 6, 5}};
    private static final int[][][] DISTANCE = new int[9][3][3];

    static {
        for (int num = 1; num <= 8; num++) {
            for (int i = 0; i < 3; i++) {
                for (int j = 0; j < 3; j++) {
                    DISTANCE[num][i][j] = Math.abs(i - (num - 1) / 3) + Math.abs(j - (num - 1) % 3);
                }
            }
        }
    }

    private static class State implements Comparable<State> {
        int[][] board;
        int g;
        int h;
        State prev;

        State(int[][] board, int g, State prev) {
            this.board = board;
            this.g = g;
            this.h = calculateH(board);
            this.prev = prev;
        }

        int f() {
            return g + h;
        }

        @Override
        public int compareTo(State o) {
            return Integer.compare(f(), o.f());
        }

        boolean isGoal() {
            return Arrays.deepEquals(board,