백준 2178 미로 탐색(JAVA)

문제 설명

https://www.acmicpc.net/problem/2178

 

풀이과정

 최단거리이므로 BFS를 이용해서 풀이한다.

 

정답코드

import java.io.*;
import java.util.*;

public class Main {
    static int[] dy = {-1, 1, 0, 0};
    static int[] dx = {0, 0, -1, 1};
    static int[][] board;
    static boolean[][] visited;
    static int N, M;

    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));
        StringTokenizer st = new StringTokenizer(br.readLine());

        N = Integer.parseInt(st.nextToken());
        M = Integer.parseInt(st.nextToken());

        board = new int[N][M];
        visited = new boolean[N][M];

        for (int i = 0; i < N; i++) {
            String input = br.readLine();
            for (int j = 0; j < M; j++) {
                board[i][j] = input.charAt(j) - '0';
            }
        }

        bfs(0, 0);

        bw.write(String.valueOf(board[N - 1][M - 1]));
        bw.flush();
    }

    public static void bfs(int startY, int startX) {
        Queue<int[]> queue = new LinkedList<>();
        queue.add(new int[] {startY, startX});
        visited[startY][startX] = true;

        while (!queue.isEmpty()) {
            int[] current = queue.poll();
            int y = current[0];
            int x = current[1];

            for (int i = 0; i < 4; i++) {
                int ny = y + dy[i];
                int nx = x + dx[i];

                if (ny >= 0 && ny < N && nx >= 0 && nx < M) {
                    if (!visited[ny][nx] && board[ny][nx] == 1) {
                        board[ny][nx] = board[y][x] + 1;
                        visited[ny][nx] = true;
                        queue.add(new int[] {ny, nx});
                    }
                }
            }
        }
    }
}