<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:
    bool bfs(int i , int j , vector<vector<int>>&grid){
        int n = grid.size();
        int m = grid[0].size();
        queue<pair<int , int>>q;
        q.push({i , j});
        bool ans = true;
        vector<vector<int>>dir = {{0 , 1},{0 , -1},{1 , 0},{-1 , 0}};
        while(!q.empty()){
            auto curr = q.front();
            q.pop();
            int row = curr.first;
            int col = curr.second;
            for(auto it : dir){
                int nrow = row + it[0];
                int ncol = col + it[1];
                if(nrow < 0 || ncol < 0 || nrow  >= n || ncol >= m || grid[nrow][ncol] == 1){
                    continue;
                }
                if(nrow == 0 || ncol == 0 || nrow == n -1 || ncol == m - 1){
                    ans = false;
                }
                grid[nrow][ncol] = 1;
                q.push({nrow , ncol});
            }
            
        }
        return ans;
    }
    int closedIsland(vector<vector<int>>& grid) {
        int n = grid.size();
        int m = grid[0].size();
        int answer = 0 ;
        
        vector<vector<int>>vis(n , vector<int>(m , 0));
        for(int i = 1 ; i < n - 1 ; i++){
            for(int j = 1 ; j < m - 1 ; j++){
                if(grid[i][j] == 0){
                    bool count = bfs(i , j , grid);
                    answer += count;
                }
            }
        }
        return answer;
        
    }
};
23006