섬나라 아일랜드(BFS)

풀이에 Pointer 클래스를 사용한 것 이외에는 거의 비슷하다

import java.util.*;

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

class Main{

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

    static int[][] board;

    static Queue<Pointer> Q = new LinkedList<>();
    static int res = 0, n;

    public void Solution(){
        for (int i = 0; i < n; i++){
            for (int j = 0; j < n; j++){
                if (board[i][j] == 1){
                    board[i][j] = 0;
                    res++;
                    BFS(i, j);
                }
            }
        }
    }

    public void BFS(int i, int j){
        Q.add(new Pointer(i, j));
        while (!Q.isEmpty()){
            Pointer tmp = Q.poll();
            for (int k = 0; k < 8; k++){
                int nx = tmp.x+ dx[k];
                int ny = tmp.y + dy[k];
                if (nx >= 0 && nx < n && ny >= 0 && ny < n && board[nx][ny] == 1){
                    board[nx][ny] = 0;
                    Q.add(new Pointer(nx, ny));
                }
            }
        }

    }

    public static void main(String[] args) {
        Main T = new Main();
        Scanner in = new Scanner(System.in);
        n = in.nextInt();
        board = new int[n][n];
        for (int i = 0; i < n; i++){
            for (int j = 0; j < n; j++){
                board[i][j] = in.nextInt();
            }
        }

        T.Solution();
        System.out.println(res);
    }
}