Pool

import java.io.File;
import java.io.FileNotFoundException;
import java.util.Scanner;

public class Pool {

static int[][] field;
static int nums=0;
static int[][] dir = new int[][] { { -1, 0 }, { 1, 0 }, { 0, -1 }, { 0, 1 } };

public static void main(String[] args) throws FileNotFoundException {
    // TODO Auto-generated method stub
    Scanner sc = new Scanner(new File("src/pool"));
    int N=sc.nextInt();
    field=new int[N+2][N+2];
    for(int i=0;i<N+2;i++){
        field[i][0]=0;
        field[0][i]=0;
        field[i][N+1]=0;
        field[N+1][i]=0;
    }
    for(int i=1;i<N+1;i++){
        for(int j=1;j<N+1;j++){
            field[i][j]=sc.nextInt();
        }
    }
    for(int i=1;i<N+1;i++){
        for(int j=1;j<N+1;j++){
            if(field[i][j]==1){
                nums++;
                Markpool(i,j,nums+1);
            }
        }
    }
    System.out.println(nums);
}

private static void Markpool(int x, int y, int seq) {
    // TODO Auto-generated method stub
    if(field[x][y]!=1)
        return;
    field[x][y]=seq;
    for(int i=0;i<4;i++){
        Markpool(x + dir[i][0], y + dir[i][1], seq);
    }
}

}