<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 {
public:
    int numEnclaves(vector<vector<int>>& grid) {
        queue<pair<int, int>> q;

        for (int i = 0; i < grid.size(); i++) {
            for (int j = 0; j < grid[0].size(); j++) {
                if (i == 0 || j == 0 || i == grid.size() - 1 || j == grid[0].size() - 1 ) {
                    if(grid[i][j]==1){
                    q.push(make_pair(i, j));
                    grid[i][j]=-1;}
                }
            }
        }

        for(auto a1:grid)
        {
            for(auto a2:a1)
            cout<<a2<<" ";
            cout<<endl;
        }

        while (!q.empty()) {
            auto node = q.front();
            q.pop();
            vector<pair<int, int>> dirn = {{0, 1}, {1, 0}, {-1, 0}, {0, -1}};
            
            for(auto& dir : dirn)
            {
                int ix = dir.first + node.first;
                int iy = dir.second + node.second;

                if(ix>=0 && iy>=0 && ix<grid.size() && iy<grid[0].size() && grid[ix][iy]==1)
                {
                    q.push(make_pair(ix,iy));
                    grid[ix][iy]=-1;
                }
            }
        }
        int count=0;

        for (int i = 0; i < grid.size(); i++) {
            for (int j = 0; j < grid[0].size(); j++) {
               if(grid[i][j]==1)
               count++;
                }
            }
        return count;
        
    }
};
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