Dfs+回溯--迷宫问题1.1

深度优先访问+回溯实现迷宫问题

1为墙，0为可走的路，代码有注释。

import java.util.Scanner;
public class maze {
    //地图的大小
    //用来保存地图
    static int n = 6, m = 5, start_x, start_y, end_x, end_y;
    //n22 m21
//    static int[][] map = {
//            {1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1},
//            {1, 0, 1, 0, 1, 1, 1, 1, 1, 1, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 1},
//            {1, 0, 1, 0, 0, 0, 0, 0, 0, 1, 0, 0, 1, 0, 0, 0, 1, 0, 1, 0, 1},
//            {1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1},
//            {1, 1, 1, 0, 0, 0, 1, 0, 0, 1, 0, 0, 1, 0, 1, 0, 1, 0, 0, 0, 1},
//            {1, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1},
//            {1, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 1, 0, 0, 0, 1},
//            {1, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 1, 0, 1, 0, 0, 0, 1},
//            {1, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 1, 0, 1, 0, 0, 0, 1},
//            {1, 0, 1, 0, 0, 1, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1},
//            {1, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1},
//            {1, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 1, 0, 1},
//            {1, 0, 1, 0, 1, 0, 1, 1, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 1, 0, 1},
//            {1, 0, 1, 0, 0, 0, 1, 1, 1, 0, 1, 0, 0, 1, 1, 0, 1, 0, 1, 0, 1},
//            {1, 0, 0, 0, 1, 0, 1, 0, 1, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1},
//            {1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 0, 0, 1},
//            {1, 0, 1, 0, 0, 0, 1, 0, 1, 0, 0, 0, 1, 0, 1, 0, 0, 0, 1, 0, 1},
//            {1, 0, 1, 0, 0, 1, 1, 0, 1, 1, 0, 0, 1, 0, 1, 0, 0, 0, 0, 1, 1},
//            {1, 1, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1},
//            {1, 0, 1, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 1, 0, 0, 1, 0, 0, 0, 1},
//            {1, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1},
//            {1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1}};

////    n=6，m=5
    static int[][] map = {
        {1,1,1,1,1},
        {1,0,0,0,1},
        {1,0,1,0,1},
        {1,0,1,0,1},
        {1,0,0,0,1},
        {1,1,1,1,1}};
    //用来保存是否被访问过
    static int[][] isVisited = new int[n][m];
    //记录所有可行路径下标
    static int[][] train = new int[2500][2];
    //遵循 左下右上 的顺序
    static int[][] path = {{0, -1},
            {1, 0},
            {0, 1},
            {-1, 0}};
    //记录所有到达的路径数量
    static int count;
    //记录走的步数，方便回溯打印
    static int k;
    //判断是否已经到达终点
    static int flag;
    static boolean f = false;

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        //输出地图
        System.out.println("地图的情况");
        for (int i = 0; i < n; i++) {
            for (int j = 0; j < m; j++) {
                System.out.print(map[i][j] + " ");
            }
            System.out.println();
        }
//        System.out.println("（1，1）（1，19）可作为起点---（20，19）（20，3）可作为终点---也可另寻别路");
        //输入判断操作
        while (!f) {
            System.out.print("请输入起点坐标:");
            start_x = sc.nextInt();
            start_y = sc.nextInt();
            System.out.print("请输入终点坐标:");
            end_x = sc.nextInt();
            end_y = sc.nextInt();
            //判断要查询的起点和终点坐标 是否符合标准
            if (!isStandard(start_x, start_y)) {
                System.out.println("输入的起点坐标有误~~~");
            } else if (!isStandard(end_x, end_y)) {
                System.out.println("输入的终点坐标有误~~~");
            } else if (start_x == end_x && start_y == end_y) {
                System.out.println("起点终点不能相同~~~");
            } else {
                dfs(start_x, start_y);
                if (count == 0) {
                    System.out.println("没路");
                }
                return;
            }
        }

    }


    //传进来起点坐标
    public static void dfs(int x, int y) {
        if (x == end_x && y == end_y) {
            count++;
            printPath();
            return;
        }
        for (int i = 0; i < path.length; i++) {
            //开始四个方向分别遍历
            int next_x = x + path[i][0];
            int next_y = y + path[i][1];
            isVisited[x][y] = 1;
            //判断是否符合标准
            if (isStandard(next_x, next_y)) {
                isVisited[next_x][next_y] = 1;
                train[k][0] = x;
                train[k][1] = y;
                k++;
                //进行递归寻找下一个可行的路
                dfs(next_x,next_y);
                //若到了终点置零
                isVisited[next_x][next_y] = 0;
                k--;
            }
        }
    }
    //打印走过的路径
    public static void printPath() {
        for(int i = 0;i<=k-1;i++){
            System.out.print("[" + train[i][0] + "," + train[i][1] + "]"+"->");
        }
        System.out.print("[" + end_x + "," + end_y + "]");
        System.out.println();
    }
    //判断这个点是否符合标准
    static boolean isStandard(int x, int y) {
        if (x < n && x > 0 && y > 0 && y < m && map[x][y] == 0 && isVisited[x][y] == 0) {
            return true;
        }
        return false;
    }
}