programmers_리코쳇 로봇_java

https://school.programmers.co.kr/learn/courses/30/lessons/169199

프로그래머스

import java.util.*;

class Solution {
    private static int[][] delta = {{0,1} , {1, 0}, {0, -1}, {-1, 0}};

    public int solution(String[] board) {
        int answer = 0;

        // start 찾기
        int y = 0;
        for (String s : board){
            boolean res = false;
            for (int i = 0; i< s.length(); i++){
                if (s.charAt(i) == 'R'){
                    answer = bfs(board, new int[]{y, i});
                    res = true;
                    break;
                }
            }
            if (res) break;
            y++;
        }


        return answer;
    }

    //bfs 탐색
    public int bfs(String[] board, int[] start){
        Queue<int[]> queue = new LinkedList<>();
        queue.offer(start);

        int width = board[0].length();
        int height = board.length;
        boolean[][] visited = new boolean[height][width];

        int cnt = 0;
        while (!queue.isEmpty()){
            int size = queue.size();
            for (int i = 0; i<size; i++){
                int[] now = queue.poll();

                if (visited[now[0]][now[1]]) continue;
                visited[now[0]][now[1]] = true;
                
                if (board[now[0]].charAt(now[1]) == 'G'){
                    return cnt;
                }

                for (int j = 0; j<4; j++){
                    queue.offer(move(now, j, width, height, board));
                }
            }
            cnt++;
        }
        return -1;
    }

    //dir 방향으로 계속 이동
    public int[] move(int[] start, int dir, int width, int height, String[] board){
        int[] now = new int[2];
        now[0] = start[0];
        now[1] = start[1];

        while (true){
            int nexty = now[0] + delta[dir][0];
            int nextx = now[1] + delta[dir][1];
            if (0<=nexty && nexty < height
                    && 0<= nextx && nextx < width
                    && board[nexty].charAt(nextx) != 'D'
            ){
                now[0] = nexty;
                now[1] = nextx;
            }else {
                return now;
            }
        }
    }
}