[프로그래머스] 1844 게임 맵 최단거리

문제

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

풀이

기본적인 BFS 문제

코드

import java.util.LinkedList;
import java.util.Queue;

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

class Solution {
    
    int[][] visited;
    int[] dx = {0, 0, 1, -1};
    int[] dy = {1, -1, 0, 0}; // 상하좌우
    
    public int solution(int[][] maps) {
        int answer = 0;
        
        int n = maps.length;
        int m = maps[0].length;
        
        visited = new int[n][m];
        
        // bfs
        BFS(n, m, maps, visited, new point(0, 0));

        answer = visited[n-1][m-1] > 0 ? visited[n-1][m-1] : -1;
        return answer;
    }
    
    public void BFS(int n, int m, int[][] maps, int[][] visited, point start){
        
        Queue<point> q = new LinkedList<>();
        q.add(start);
        visited[start.x][start.y] = 1;
        
        while(!q.isEmpty()){
            point now = q.poll();
            
            for(int i=0; i<4; i++){
                int nextX = now.x + dx[i];
                int nextY = now.y + dy[i];
                
                if(nextX >= 0 && nextY >= 0 && nextX < n && nextY < m && maps[nextX][nextY] == 1 && visited[nextX][nextY] == 0){
                    q.add(new point(nextX, nextY));
                    visited[nextX][nextY] = visited[now.x][now.y]+1;
                }
            }
        }
    }
    
    
}