<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 row, int col, vector<vector<int>>&grid, vector<vector<int>>&vis){
    int n=grid.size();
    int m=grid[0].size();
    vis[row][col]=1;
    // move[row][col]=1;
    vector<int>delr={-1,0,1,0};
    vector<int>delc={0,1,0,-1};
    for(int k=0; k<4; k++){
        int newr=row+delr[k];
        int newc=col+delc[k];
        if(newr>=0 && newr<n && newc>=0 && newc<m && grid[newr][newc]==1 && vis[newr][newc]!=1){
             dfs(newr, newc, grid, vis);
        }
    }
    return;
}
    int numEnclaves(vector<vector<int>>& grid) {
        int n=grid.size();
        int m=grid[0].size();
        vector<vector<int>>vis(n, vector<int>(m, 0));
        // vector<vector<int>>move(n,vector<int>(m,0));
        for(int i=0; i<n; i++){
            for(int j=0; j<m; j++){
                if(i==0 || i==n-1 || j==0 || j==m-1){
                    if(grid[i][j]==1){
                        dfs(i,j,grid, vis);
                    }
                }
            }
        }
        int ans=0;
        for(int i=0; i<n; i++){
            for(int j=0; j<m; j++){
                if(grid[i][j]==1 && vis[i][j]==0){
                    ans++;
                }
            }
        }
        return ans;
    }
};
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