https://school.programmers.co.kr/learn/courses/30/lessons/1844

Problem

Code

import java.util.*;

class Point {
    public int x, y;
    Point (int x, int y) {
        this.x = x;
        this.y = y;
    }
}

class Solution {
    int[] dx = {-1 , 0, 1, 0};
    int[] dy = {0, 1, 0, -1};
    int n, m;
    int[][] route, dis;
    
    public void BFS(int x, int y) {
        Queue<Point> q = new LinkedList<>();
        q.offer(new Point(x,y));
        route[x][y] = 0;
        dis[x][y] = 1;
        while(!q.isEmpty()) {
            Point tmp = q.poll();
            for (int i=0; i<4; i++) {
                int nx = tmp.x + dx[i];
                int ny = tmp.y + dy[i];
                if (nx >=0 && nx <= n && ny >=0 && ny <=m && route[nx][ny] == 1) {
                    route[nx][ny] = 0;
                    q.offer(new Point(nx,ny));
                    dis[nx][ny] = dis[tmp.x][tmp.y] + 1;
                }
            }
        }
    }
    
    public int solution(int[][] maps) {
        n = maps.length - 1;
        m = maps[0].length - 1;
        route = maps;
        dis = new int[n+1][m+1];
        BFS(0,0);
        if (dis[n][m] == 0) return -1;
        else return dis[n][m];
    }
}

Result