Count Islands, Java

Count Islands

/**
 *  Count Islands
 *  Given a 2D matrix representing a map, with 1 being path and 0 being water,
 *  find the count of islands.
 *
 *  @author: Jayesh Chandrapal
 */

import java.util.*;
import java.lang.*;

class IslandsCount {
    int N;
    
    public int countIslands() {
        int count = 0;
        int[][] matrix = readInput();
        
        for(int i = 0; i < N; i++) {
            for(int j = 0; j < N; j++) {
                if(isConnected(i, j, matrix)) {
                    count++;
                }
            }
        }
        
        return count;
    }
    
    public boolean isConnected(int i, int j, int[][] matrix) {
        if(!isValidIndex(i, j, matrix.length)) {
            return false;
        }
        
        if(matrix[i][j] == 1) {
            matrix[i][j] = 0;
            
            isConnected(i + 1, j, matrix);
            isConnected(i - 1, j, matrix);
            isConnected(i, j + 1, matrix);
            isConnected(i, j - 1, matrix);
            isConnected(i + 1, j + 1, matrix);
            isConnected(i + 1, j - 1, matrix);
            isConnected(i - 1, j - 1, matrix);
            isConnected(i - 1, j + 1, matrix);
            
            return true;
        }
        
        return false;
    }
    
    public boolean isValidIndex(int x, int y, int n) {
        return !(x < 0 || x >= n || y < 0 || y >= n);
    }
    
    public int[][] readInput() {
        Scanner in = new Scanner(System.in);
        N = in.nextInt();
        int[][] matrix = new int[N][N];
        
        for(int i = 0; i < N; i++) {
            for(int j = 0; j < N; j++) {
                matrix[i][j] = in.nextInt();
            }
        }
        
        return matrix;
    }
}

class Rextester
{  
    public static void main(String args[])
    {
        IslandsCount app = new IslandsCount();
        System.out.println(app.countIslands());
    }
}


run \| edit \| history \| help	0