<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:

        def get_unvisited_neighbours(row, col, grid, visited):
            unvisited_neighbours = []
            if row > 0 and not visited[row-1][col]:
                unvisited_neighbours.append([row-1, col])
        
            if col > 0 and not visited[row][col-1]:
                unvisited_neighbours.append([row, col-1])
        
            if row < len(grid)-1 and not visited[row+1][col]:
                unvisited_neighbours.append([row+1, col])
        
            if col < len(grid[0])-1 and not visited[row][col+1]:
                unvisited_neighbours.append([row, col+1])
            return unvisited_neighbours

        def explore(grid, row, col, visited):
            nodes_to_explore = [[row, col]]

            while len(nodes_to_explore) > 0:
                row, col = nodes_to_explore.pop()

                if visited[row][col]:
                    continue
                if grid[row][col] == 0:
                    continue
            
                visited[row][col] = True
                unvisited_neighbours = get_unvisited_neighbours(row, col, grid, visited)
                for neighbour in unvisited_neighbours:
                    nodes_to_explore.append(neighbour)

        visited = [[False for y in range(len(grid[0]))] for x in range(len(grid))]
        for j in range(len(grid[0])):
            explore(grid, 0, j, visited)
            explore(grid, len(grid)-1, j, visited)
        
        for i in range(len(grid)):
            explore(grid, i, 0, visited)
            explore(grid, i, len(grid[0])-1, visited)
        
        count = 0
        for i in range(1, len(grid)-1):
            for j in range(1, len(grid[0])-1):
                if visited[i][j] == False and grid[i][j] == 1:
                    count += 1
        
        return count


        
23004