o g 寻找最短

给一个矩阵，每个格子上有三种可能，空房，阻碍物或者是保安，阻碍物不能进，空房
四个方向都能进，要写代码给每个空房标记其离最近的保安的距离，比如

000
BGG
B00

B表示障碍物，G表示保安，0表示空房，应该标记为

211
BGG
B11

import java.util.ArrayList;

import java.util.LinkedList;

import java.util.Queue;

import java.util.Stack;

public class xddd {
/**

     * @param args

     */

    class Node{

        int x, y;

        int step;

        Node(int x, int y,  int step){

            this.x = x;

            this.y = y;

            this.step = step;

        }

    }
char[][] martrix ;

    int[][] stepArr = {{-1, 0}, {0, -1}, {1, 0}, {0, 1}};

    public xddd() {

        // TODO Auto-generated constructor stub

        martrix = new char[][]{{‘0‘,‘0‘,‘0‘},{‘B‘,‘G‘,‘G‘},{‘B‘,‘0‘,‘0‘}};

    }
public static void printmar(char[][] martrix){

        for(int i=0; i<martrix.length;i++){

            System.out.println(" ");

            for(int j=0; j<martrix[0].length; j++)

                System.out.print(martrix[i][j]);

        }
}

    public int bfs(char[][] martrix, int ix, int iy){

        int[][] visit = new int[3][3];//标记是否已经访问过
Node node = new Node(ix, iy, 0);

        Queue<Node> queue = new LinkedList<Node>();

        queue.offer(node);

        int M = martrix.length;

        int N = martrix[0].length;

        while(!queue.isEmpty()){

            Node head = queue.poll();

            visit[head.x][head.y] = 1;

            for(int i = 0; i < 4; i++){

                int x = head.x + stepArr[i][0];

                int y = head.y + stepArr[i][1];

                //exit

                if(x >= 0 && x < M && y >= 0 && y < N &&martrix[x][y] == ‘G‘){

                    return head.step+1;

                }

                //bfs

                if(x >= 0 && x < M && y >= 0 && y < N &&martrix[x][y] == ‘0‘ && visit[x][y] == 0){
System.out.println(x + " " +y + head.step);

                    Node newNode = new Node(x, y, head.step + 1);

                    queue.offer(newNode);

                }
}

        }

        return -1;

    }
public static void main(String[] args) {

        // TODO Auto-generated method stub

         xddd x = new xddd();

         printmar(x.martrix);

         char[][] ret = new char[3][3];

            for(int i=0; i<x.martrix.length;i++){

                System.out.println(" ");

                for(int j=0; j<x.martrix[0].length; j++){

                    if(x.martrix[i][j] != ‘0‘)

                        ret[i][j] = x.martrix[i][j];

                    else{

                        ret[i][j] = (char)(‘0‘ + x.bfs(x.martrix,i,j));

                    }

                }
}
printmar(ret);

    }
}

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