[Java] BFS 구현

import java.util.*;

public class Main {
	public static boolean [][] vis = new boolean[502][502];
	public static int [][] board = new int[502][502];
	public static int n,m; // n > 행 m > 열
	public static int [] dx = {1,0,-1,0};
	public static int [] dy = {0,1,0,-1};
    public static void main(String[] args){
    	Scanner sc = new Scanner(System.in);
    	n = sc.nextInt();
    	m = sc.nextInt();
    	
    	for(int i=0;i<n;i++) {
    		for(int j=0;j<m;j++) {
    			board[i][j] = sc.nextInt();
    		}
    	}
    	
    	Queue<Pos> q = new LinkedList<>();
    	
    	for(int i=0;i<n;i++) {
    		for(int j=0;j<m;j++) {
    			if(board[i][j] == 1 && vis[i][j] == false) {
    				vis[i][j] = true;
    		    	q.add(new Pos(i,j));
    		    	
    		    	while(!q.isEmpty()) {
    		    		Pos cur = q.poll();// 큐에서 하나 뽑아냄
    		    		for(int dir = 0;dir<4;dir++) {
    		    			int nx = cur.x + dx[dir];
    		    			int ny = cur.y + dy[dir];
    		    			if(nx < 0 || nx >=n || ny < 0 || ny >= m) continue;
    		    			if(vis[nx][ny] || board[nx][ny] != 1) continue;
    		    			vis[nx][ny] = true;
    		    			q.add(new Pos(nx,ny));
    		    		}
    		    	}
    			}
    		}
    	}
    }
}

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

 

https://nahwasa.com/entry/BFS-%EC%95%8C%EA%B3%A0%EB%A6%AC%EC%A6%98-%EB%84%88%EB%B9%84-%EC%9A%B0%EC%84%A0-%ED%83%90%EC%83%89-%EB%B0%B0%EC%97%B4-BFS-%EA%B7%B8%EB%9E%98%ED%94%84-BFS

BFS 알고리즘 (너비 우선 탐색) - 배열 BFS, 그래프 BFS (2022-07-21 업데이트)

https://github.com/encrypted-def/basic-algo-lecture/blob/master/0x09/BFS.cpp

GitHub - encrypted-def/basic-algo-lecture: 바킹독의 실전 알고리즘 강의 자료