1020. Number of Enclaves

T: O(mn)

S: O(1)

```java
class Solution {
    private int m;
    private int n;
    private static final int[][] DIRECTIONS = {{0,1},{1,0}, {0,-1},{-1,0}};
    public int numEnclaves(int[][] grid) {
        m = grid.length;
        n = grid[0].length;

        // exclude edge connected land
        for (int i = 0; i < m ; i++) {
            for (int j = 0; j < n; j++) {
                if ((i == 0 || i == m-1 || j == 0 || j == n-1) && grid[i][j] == 1) { 
                    dfs(grid, i, j);
                }
            }
        }

        // only need to count left 1 (moves)
        int count = 0;
        for (int i = 0; i < m ; i++) {
            for (int j = 0; j < n; j++) {
                if (grid[i][j] == 1) { 
                    count++;
                }
            }
        }
        return count;
    }

    // flood fill dfs
    private void dfs(int[][] grid, int i, int j) {
        if (i < 0 || i >= m || j < 0 || j >= n || grid[i][j] != 1) {
            return;
        }
        grid[i][j] = 0;
        for (int[] direction : DIRECTIONS) {
           dfs(grid, i + direction[0], j + direction[1]);
        }
    }
}
```