<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:
    void dfs(int r,int c,vector<vector<int>>& grid,vector<vector<int>>& visited,int rows,int cols){
        visited[r][c]=1;
        vector<pair<int,int>>v{{r+1,c},{r-1,c},{r,c+1},{r,c-1}};
        for(auto& p:v){
            int x=p.first;
            int y=p.second;
            if(x>=0&&y>=0&&x<rows&&y<cols){
                if(grid[x][y]==1&&visited[x][y]==0){
                    dfs(x,y,grid,visited,rows,cols);
                }
            }
        }
    }
    int numEnclaves(vector<vector<int>>& grid) {
        int rows=grid.size();
        int cols=grid[0].size();
        vector<vector<int>>visited(rows,vector<int>(cols,0));
        for(int i=0;i<rows;i++){
            if(visited[i][0]!=1&&grid[i][0]==1){
                dfs(i,0,grid,visited,rows,cols);
            }

            if(visited[i][cols-1]!=1&&grid[i][cols-1]==1){
                dfs(i,cols-1,grid,visited,rows,cols);
            }
            
            
        }
        for(int i=0;i<cols;i++){
            if(visited[0][i]!=1&&grid[0][i]==1){
                dfs(0,i,grid,visited,rows,cols);
            }
            if(visited[rows-1][i]!=1&&grid[rows-1][i]==1){
                 dfs(rows-1,i,grid,visited,rows,cols);
            }
            
           
        }
        int c=0;
        for(int i=0;i<rows;i++){
            for(int j=0;j<cols;j++){
                if(grid[i][j]==1&&visited[i][j]!=1){
                    c++;
                }
            }
        }
        return c;
    }
};
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