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# Number of Enclaves

Given a 2D array `A`, each cell is 0 (representing sea) or 1 (representing land)

A move consists of walking from one land square 4-directionally to another land square, or off the boundary of the grid.

Return the number of land squares in the grid for which we **cannot** walk off the boundary of the grid in any number of moves.

**Example 1:**

```
Input: [[0,0,0,0],[1,0,1,0],[0,1,1,0],[0,0,0,0]]
Output: 3
Explanation: 
There are three 1s that are enclosed by 0s, and one 1 that isn't enclosed because its on the boundary.
```

**Example 2:**

```
Input: [[0,1,1,0],[0,0,1,0],[0,0,1,0],[0,0,0,0]]
Output: 0
Explanation: 
All 1s are either on the boundary or can reach the boundary.
```

**Note:**

1. `1 <= A.length <= 500`
2. `1 <= A[i].length <= 500`
3. `0 <= A[i][j] <= 1`
4. All rows have the same size.

```java
class Solution {
    public int numEnclaves(int[][] A) {
        if (A.length == 0)
            return 0;
        // Marking boundary land area
        boolean[][] visited = new boolean[A.length][A[0].length];
        for (int i = 0; i < A.length; i++) {
            if (!visited[i][0])
                markerDFS(A, visited, i, 0);
            if (!visited[i][A[0].length - 1])
                markerDFS(A, visited, i, A[0].length - 1);
        }
        for (int j = 0; j < A[0].length; j++) {
            if (!visited[0][j])
                markerDFS(A, visited, 0, j);
            if (!visited[A.length - 1][j])
                markerDFS(A, visited, A.length - 1, j);
        }
        int count = 0;
        for (int i = 1; i < A.length - 1; i++) {
            for (int j = 1; j < A[0].length - 1; j++) {
                if (!visited[i][j] && A[i][j] == 1)
                    count++;
            }
        }
        return count;
    }

    public void markerDFS(int[][] grid, boolean[][] visited, int x, int y) {
        if (x >= 0 && x < grid.length && y >= 0 && y < grid[0].length && !visited[x][y] && grid[x][y] == 1) {
            visited[x][y] = true;
            markerDFS(grid, visited, x + 1, y);
            markerDFS(grid, visited, x, y + 1);
            markerDFS(grid, visited, x - 1, y);
            markerDFS(grid, visited, x, y - 1);
        }
    }
}
```