[JAVA] BFS

package algo.BFS;

import java.util.*;
import java.util.stream.IntStream;

public class BFS  {
    public static void main(String[] args) {
        // [503], [503]
        int board[][] = {
            {1,1,1,0,1,0,0,0,0,0},
            {1,0,0,0,1,0,0,0,0,0},
            {1,1,1,0,1,0,0,0,0,0},
            {1,1,0,0,1,0,0,0,0,0},
            {0,1,0,0,0,0,0,0,0,0},
            {0,0,0,0,0,0,0,0,0,0},
            {0,0,0,0,0,0,0,0,0,0}
        }; //1파란칸, 0빨간칸
        int vis[][] = new int[503][503]; //해당칸 방문
        IntStream.range(0, 503)
        .forEach(i -> {
            Arrays.fill(vis[i], 0);
        });
        int n=7; int m=10; //n=행, m=열
        int dx[] = {1, 0, -1, 0};
        int dy[] = {0, 1, 0, -1}; //상하좌우

        Queue<Pair> pQ = new LinkedList<Pair>();
        vis[0][0] = 1;
        pQ.add(new Pair(0, 0));
        
        while(pQ.size() > 0){
            Pair cur = pQ.peek(); pQ.remove();
            System.out.println("("+cur.getX()+", "+cur.getY()+") -> ");
            //방향 체크
            for(int dir = 0; dir < 4; dir++){
                int nx = cur.getX() + dx[dir];
                int ny = cur.getY() + dy[dir];
                if( nx < 0 || nx >= n || ny < 0 || ny >= m) continue;
                if(vis[nx][ny] == 1 || board[nx][ny] != 1) continue; 
                vis[nx][ny] = 1; //방문
                pQ.add(new Pair(nx, ny));
            }
        }
    }
}

class Pair implements Comparable<Pair>{
    private int x;
    private int y;

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

    public int getX(){
        return this.x;
    }

    public int getY(){
        return this.y;
    }

    @Override
    public int compareTo(final Pair o){
        if(x == o.x) return Integer.compare(y, o.y);
        return Integer.compare(x, o.x);
    }
}

출처 : https://blog.encrypted.gg/941?category=773649 

[실전 알고리즘] 0x09강 - BFS