JAVA学习-练习试用Java实现“深度优先搜索（DFS）：实现八数码问题的解法（最短路径搜索）”

问题：

       java语言编辑，深度优先搜索（DFS）：实现八数码问题的解法（最短路径搜索）。

解答思路：

       为了实现八数码问题的解法，我们可以使用深度优先搜索（DFS）结合回溯算法。以下是一个Java实现，它使用递归来实现DFS，并尝试找到从初始状态到目标状态的解。

import java.util.*;class State {int[] board;int moves;State parent;int cost; // g(n)public State(int[] board, int moves, State parent, int cost) {this.board = board.clone();this.moves = moves;this.parent = parent;this.cost = cost;}// Generate all possible states from the current statepublic List<State> generateNextStates() {List<State> nextStates = new ArrayList<>();int zeroIndex = findZeroIndex();int[] directions = {-1, 1, -3, 3}; // Up, Down, Left, Rightfor (int direction : directions) {int nextIndex = zeroIndex + direction;if (nextIndex >= 0 && nextIndex < 9 && isValidMove(zeroIndex, nextIndex)) {int[] newBoard = board.clone();swap(newBoard, zeroIndex, nextIndex);nextStates.add(new State(newBoard, moves + 1, this, cost + 1));}}return nextStates;}// Find the index of the zero in the boardprivate int findZeroIndex() {for (int i = 0; i < board.length; i++) {if (board[i] == 0) {return i;}}return -1;}// Check if the move is validprivate boolean isValidMove(int fromIndex, int toIndex) {return Math.abs(fromIndex % 3 - toIndex % 3) + Math.abs(fromIndex / 3 - toIndex / 3) == 1;}// Swap two elements in the arrayprivate void swap(int[] array, int i, int j) {int temp = array[i];array[i] = array[j];array[j] = temp;}// Check if the current state is the goal statepublic boolean isGoalState(int[] goal) {for (int i = 0; i < board.length; i++) {if (board[i] != goal[i]) {return false;}}return true;}}public class EightPuzzleSolver {private static final int[] GOAL_STATE = {1, 2, 3, 4, 5, 6, 7, 8, 0};private Set<Integer> visited;public List<int[]> solve(int[] initialBoard) {visited = new HashSet<>();State start = new State(initialBoard, 0, null, 0);return dfs(start);}private List<int[]> dfs(State current) {if (visited.contains(Arrays.hashCode(current.board))) {return null;}visited.add(Arrays.hashCode(current.board));if (current.isGoalState(GOAL_STATE)) {List<int[]> path = new ArrayList<>();while (current != null) {path.add(current.board.clone());current = current.parent;}Collections.reverse(path);return path;}for (State nextState : current.generateNextStates()) {List<int[]> result = dfs(nextState);if (result != null) {return result;}}return null;}public static void main(String[] args) {int[] initialBoard = {1, 2, 3, 4, 5, 6, 7, 8, 0};EightPuzzleSolver solver = new EightPuzzleSolver();List<int[]> solution = solver.solve(initialBoard);if (solution != null) {System.out.println("Solution found:");for (int[] state : solution) {for (int num : state) {System.out.print(num + " ");}System.out.println();}} else {System.out.println("No solution found.");}}}

       这段代码定义了一个'State'类来表示八数码问题的一个状态，包括棋盘布局、移动次数、父状态和路径成本。'EightPuzzleSolver'类实现了深度优先搜索算法，并从初始状态开始搜索解。如果找到解，它会返回一个包含从初始状态到目标状态的路径的列表。'main'方法提供了一个示例初始状态，并调用'solve'方法来找到解决方案。

(文章为作者在学习java过程中的一些个人体会总结和借鉴，如有不当、错误的地方，请各位大佬批评指正，定当努力改正，如有侵权请联系作者删帖。)