<p>You are given an <code>m x n</code> binary matrix <code>grid</code>, where <code>0</code> represents a sea cell and <code>1</code> represents a land cell.</p>

<p>A <strong>move</strong> consists of walking from one land cell to another adjacent (<strong>4-directionally</strong>) land cell or walking off the boundary of the <code>grid</code>.</p>

<p>Return <em>the number of land cells in</em> <code>grid</code> <em>for which we cannot walk off the boundary of the grid in any number of <strong>moves</strong></em>.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>
<img alt="" src="https://assets.leetcode.com/uploads/2021/02/18/enclaves1.jpg" style="width: 333px; height: 333px;" />
<pre>
<strong>Input:</strong> grid = [[0,0,0,0],[1,0,1,0],[0,1,1,0],[0,0,0,0]]
<strong>Output:</strong> 3
<strong>Explanation:</strong> There are three 1s that are enclosed by 0s, and one 1 that is not enclosed because its on the boundary.
</pre>

<p><strong class="example">Example 2:</strong></p>
<img alt="" src="https://assets.leetcode.com/uploads/2021/02/18/enclaves2.jpg" style="width: 333px; height: 333px;" />
<pre>
<strong>Input:</strong> grid = [[0,1,1,0],[0,0,1,0],[0,0,1,0],[0,0,0,0]]
<strong>Output:</strong> 0
<strong>Explanation:</strong> All 1s are either on the boundary or can reach the boundary.
</pre>

<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li><code>m == grid.length</code></li>
	<li><code>n == grid[i].length</code></li>
	<li><code>1 &lt;= m, n &lt;= 500</code></li>
	<li><code>grid[i][j]</code> is either <code>0</code> or <code>1</code>.</li>
</ul>

class Solution:
    def numEnclaves(self, grid: List[List[int]]) -> int:

        rows = len(grid)
        cols = len(grid[0])
        ans = 0

        def dfs(row, col):
            grid[row][col] = 2
            rt = [0, 0, -1, 1]
            ct = [1, -1, 0, 0]

            for i in range(4):
                newr = rt[i] + row
                newc = ct[i] + col
                if isValid(newr, newc) and grid[newr][newc] == 1:
                    # print('going to ', newr, newc)
                    grid[newr][newc] = 2
                    dfs(newr, newc)

            # return [ignore, count]
                    

        def isValid(row, col):
            if row > 0 and col > 0 and row < rows and col < cols:
                return True
            return False



        def isBoundary(row, col):
            if row > 0 and col > 0 and row < rows - 1 and col < cols - 1:
                return False
            return True


        for i in range(rows):
            if grid[i][0] == 1:
                dfs(i, 0)
            if grid[i][cols - 1] == 1:
                dfs(i, cols - 1)

        for j in range(cols):
            # First row
            if grid[0][j] == 1:
                dfs(0, j)
            # Last row
            if grid[rows - 1][j] == 1:
                dfs(rows- 1, j)

        for i in range(rows - 1):
            for j in range(cols - 1):
                if grid[i][j] == 1:
                    ans += 1

        
        

        
            

        return ans



        
        
43286