695. Max Area of Island

/*
Given a non-empty 2D array grid of 0's and 1's.
An island is a group of 1's (representing land) connected 4-directionally (horizontal or vertical).
You may assume all four edges of the grid are surrounded by water.

Find the maximum area of an island in the given 2D array.
If there is no island, the maximum area is 0.

Example:

[[0,0,1,0,0,0,0,1,0,0,0,0,0],
 [0,0,0,0,0,0,0,1,1,1,0,0,0],
 [0,1,1,0,1,0,0,0,0,0,0,0,0],
 [0,1,0,0,1,1,0,0,1,0,1,0,0],
 [0,1,0,0,1,1,0,0,1,1,1,0,0],
 [0,0,0,0,0,0,0,0,0,0,1,0,0],
 [0,0,0,0,0,0,0,1,1,1,0,0,0],
 [0,0,0,0,0,0,0,1,1,0,0,0,0]]
Given the above grid, return 6.

Idea: found any not visited LAND and traverse the new island.
*/

class Solution {
    final static int LAND = 1;
    final static int WATER = 0;
    
    public int maxAreaOfIsland(int[][] grid) {
        if (grid.length == 0) {
            return 0;
        }
        boolean[][] isVisited = new boolean[grid.length][grid[0].length];

        int maxArea = 0;
        for (int i = 0; i < grid.length; i++) {
            for (int j = 0; j < grid[i].length; j++) {
                if (grid[i][j] == LAND && !isVisited[i][j]) {
                    int currentIslandArea = traverseIslandAndCountLand(grid, isVisited, i, j);
                    maxArea = Math.max(maxArea, currentIslandArea);
                }
            }
        }
        return maxArea;
    }

    // depth first search
    private int traverseIslandAndCountLand(int[][] grid, boolean[][] isVisited, int i, int j) {
        if (isVisited[i][j] || grid[i][j] == WATER) {
            return 0;
        }
        isVisited[i][j] = true;
        
        int counter = 1;
        if (isNewIslandLand(grid, isVisited, i + 1, j)) {
            counter += traverseIslandAndCountLand(grid, isVisited, i + 1, j);
        }
        if (isNewIslandLand(grid, isVisited, i - 1, j)) {
            counter += traverseIslandAndCountLand(grid, isVisited, i - 1, j);
        }
        if (isNewIslandLand(grid, isVisited, i, j + 1)) {
            counter += traverseIslandAndCountLand(grid, isVisited, i, j + 1);
        }
        if (isNewIslandLand(grid, isVisited, i, j - 1)) {
            counter += traverseIslandAndCountLand(grid, isVisited, i, j - 1);
        }
        return counter;
    }

    private boolean isNewIslandLand(int[][] grid, boolean[][] isVisited, int i, int j) {
        return i >= 0 && i < grid.length &&
                j >= 0 && j < grid[i].length &&
                !isVisited[i][j] &&
                grid[i][j] == LAND;
    }
}


//--------------------------------------------------------------------------------------------------------------------
//-------------------------------------Breadth First Solution via Queue-----------------------------------------------
//--------------------------------------------------------------------------------------------------------------------
class Solution {
  
        public int maxAreaOfIsland(int[][] grid) {
        int maxArea = 0;
        for (int i = 0; i < grid.length; i++) {
            for (int j = 0; j < grid[i].length; j++) {
                if (grid[i][j] == 1) {
                    int current = 0;
                    Queue<Point> queue = new ArrayDeque<Point>();
                    queue.add(new Point(i, j));
                    while (!queue.isEmpty()) {
                        Point point = queue.poll();
                        grid[point.i][point.j] = 0;
                        current++;
                        if (point.i + 1 < grid.length) {
                            if (grid[point.i + 1][point.j] == 1) {
                                if (!queue.contains(new Point(point.i + 1, point.j))) {
                                    queue.add(new Point(point.i + 1, point.j));
                                }
                            }
                        }
                        if (point.j + 1 < grid[point.i].length) {
                            if (grid[point.i][point.j + 1] == 1) {
                                if (!queue.contains(new Point(point.i, point.j + 1))) {
                                    queue.add(new Point(point.i, point.j + 1));
                                }
                            }
                        }
                        if (point.i - 1 >= 0) {
                            if (grid[point.i - 1][point.j] == 1) {
                                if (!queue.contains(new Point(point.i - 1, point.j))) {
                                    queue.add(new Point(point.i - 1, point.j));
                                }
                            }
                        }
                        if (point.j - 1 >= 0) {
                            if (grid[point.i][point.j - 1] == 1) {
                                if (!queue.contains(new Point(point.i, point.j - 1))) {
                                    queue.add(new Point(point.i, point.j - 1));
                                }
                            }
                        }
                    }
                    if (current > maxArea) {
                        maxArea = current;
                    }
                }
            }
        }
        return maxArea;
    }
    
     class Point {
        int i;
        int j;

        int square;

        public Point(int i, int j) {
            this.i = i;
            this.j = j;
        }

        public int getSquare() {
            return square;
        }

        public void setSquare(int square) {
            this.square = square;
        }

        @Override
        public boolean equals(Object o) {
            if (this == o) return true;
            if (o == null || getClass() != o.getClass()) return false;
            Point point = (Point) o;
            return i == point.i &&
                    j == point.j;
        }

        @Override
        public int hashCode() {
            return Objects.hash(i, j);
        }
    }
}