[프로그래머스] 미로탈출 - JAVA

https://school.programmers.co.kr/learn/courses/30/lessons/159993

프로그래머스

 

풀이

미로를 탈출하는데 레버에 먼저 들리고 출구로 가야한다.

즉, 출발지 -> 레버, 레버 -> 출구 2차례 그래프 탐색으로 최솟값을 구하면 된다.

bfs탐색을 통해 두 함수의 최솟값을 구해줬다.

 

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메모리: 77.3MB
시간: 0.42ms
언어: Java 11

import java.util.*;

class Solution {
    static class Point {
        int r;
        int c;
        int time;

        public Point(int r, int c, int time) {
            this.r = r;
            this.c = c;
            this.time = time;
        }
    }

    static char[][] board;
    static int answer;

    static int[][] vector = { { 1, 0 }, { -1, 0 }, { 0, 1 }, { 0, -1 } };

    public int solution(String[] maps) {
        board = new char[maps.length][maps[0].length()];
        int sr = 0;
        int sc = 0;
        for (int i = 0; i < maps.length; i++) {
            for (int j = 0; j < maps[0].length(); j++) {
                board[i][j] = maps[i].charAt(j);
                if (board[i][j] == 'S') {
                    sr = i;
                    sc = j;
                }
            }
        }

        answer = findRoute(sr, sc, 'L');

        return answer;
    }

    private static int findRoute(int r, int c, char goal) {
        Queue<Point> queue = new LinkedList<>();

        boolean[][] visit = new boolean[board.length][board[0].length];

        visit[r][c] = true;
        queue.add(new Point(r, c, 0));

        while (!queue.isEmpty()) {
            Point curr = queue.poll();

            if (board[curr.r][curr.c] == goal) {
                if (goal == 'L') {
                    int f = findRoute(curr.r, curr.c, 'E');
                    if (f == -1) {
                        return -1;
                    } else {
                        return curr.time + f;
                    }
                } else {
                    return curr.time;
                }

            }

            for (int i = 0; i < 4; i++) {
                int nr = curr.r + vector[i][0];
                int nc = curr.c + vector[i][1];

                if (nr < 0 || nc < 0 || nr >= board.length || nc >= board[0].length || board[nr][nc] == 'X'
                        || visit[nr][nc]) {
                    continue;
                }

                queue.add(new Point(nr, nc, curr.time + 1));
                visit[nr][nc] = true;

            }

        }

        return -1;
    }
}