<p>Given a 2D&nbsp;<code>grid</code> consists of <code>0s</code> (land)&nbsp;and <code>1s</code> (water).&nbsp; An <em>island</em> is a maximal 4-directionally connected group of <code><font face="monospace">0</font>s</code> and a <em>closed island</em>&nbsp;is an island <strong>totally</strong>&nbsp;(all left, top, right, bottom) surrounded by <code>1s.</code></p>

<p>Return the number of <em>closed islands</em>.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>

<p><img alt="" src="https://assets.leetcode.com/uploads/2019/10/31/sample_3_1610.png" style="width: 240px; height: 120px;" /></p>

<pre>
<strong>Input:</strong> grid = [[1,1,1,1,1,1,1,0],[1,0,0,0,0,1,1,0],[1,0,1,0,1,1,1,0],[1,0,0,0,0,1,0,1],[1,1,1,1,1,1,1,0]]
<strong>Output:</strong> 2
<strong>Explanation:</strong> 
Islands in gray are closed because they are completely surrounded by water (group of 1s).</pre>

<p><strong class="example">Example 2:</strong></p>

<p><img alt="" src="https://assets.leetcode.com/uploads/2019/10/31/sample_4_1610.png" style="width: 160px; height: 80px;" /></p>

<pre>
<strong>Input:</strong> grid = [[0,0,1,0,0],[0,1,0,1,0],[0,1,1,1,0]]
<strong>Output:</strong> 1
</pre>

<p><strong class="example">Example 3:</strong></p>

<pre>
<strong>Input:</strong> grid = [[1,1,1,1,1,1,1],
&nbsp;              [1,0,0,0,0,0,1],
&nbsp;              [1,0,1,1,1,0,1],
&nbsp;              [1,0,1,0,1,0,1],
&nbsp;              [1,0,1,1,1,0,1],
&nbsp;              [1,0,0,0,0,0,1],
               [1,1,1,1,1,1,1]]
<strong>Output:</strong> 2
</pre>

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

<ul>
	<li><code>1 &lt;= grid.length, grid[0].length &lt;= 100</code></li>
	<li><code>0 &lt;= grid[i][j] &lt;=1</code></li>
</ul>

class Solution {
public:
    void dfsUtil(vector<vector<int>>& grid,vector<vector<int>>&vis,vector<int>delRow,vector<int>delCol,int row,int col,int n,int m)
    {
        vis[row][col] = 1;

        for(int i = 0;i<4;i++)
        {
            int nrow = row + delRow[i];
            int ncol = col + delCol[i];

            if(nrow>=0 && nrow<n && ncol>=0 && ncol<m && grid[nrow][ncol] == 0 && vis[nrow][ncol] == 0)
            {
                dfsUtil(grid,vis,delRow,delCol,nrow,ncol,n,m);
            } 
        }
    }

    int closedIsland(vector<vector<int>>& grid) {
        int n = grid.size();
        int m = grid[0].size();
        vector<vector<int>> vis(n,vector<int>(m,0));

        vector<int> delRow{-1,0,+1,0};
        vector<int> delCol{0,+1,0,-1};

        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] == 0){
                        dfsUtil(grid,vis,delRow,delCol,i,j,n,m);
                    }
                }
            }
        }
        int ans = 0;
    //     vector<vector<int>> visited(n,vector<int>(m,0));

        for(int i = 0;i<n;i++)
        {
            for(int j = 0;j<m;j++)
            {
                if(grid[i][j] == 0 && !vis[i][j])
                {
                    ans++;
                    dfsUtil(grid,vis,delRow,delCol,i,j,n,m);
                }
            }
        }
        for(int i = 0;i<n;i++)
        {
            for(int j = 0;j<m;j++)
            {
                cout<<vis[i][j]<<" ";
            }
            cout<<endl;
        }
        return ans;
    // }
    }
};
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