<p>You are given an <code>m x n</code> binary grid <code>grid</code> where <code>1</code> represents land and <code>0</code> represents water. An <strong>island</strong> is a maximal <strong>4-directionally</strong> (horizontal or vertical) connected group of <code>1</code>&#39;s.</p>

<p>The grid is said to be <strong>connected</strong> if we have <strong>exactly one island</strong>, otherwise is said <strong>disconnected</strong>.</p>

<p>In one day, we are allowed to change <strong>any </strong>single land cell <code>(1)</code> into a water cell <code>(0)</code>.</p>

<p>Return <em>the minimum number of days to disconnect the grid</em>.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>
<img alt="" src="https://assets.leetcode.com/uploads/2021/12/24/land1.jpg" style="width: 500px; height: 169px;" />
<pre>
<strong>Input:</strong> grid = [[0,1,1,0],[0,1,1,0],[0,0,0,0]]

<strong>Output:</strong> 2
<strong>Explanation:</strong> We need at least 2 days to get a disconnected grid.
Change land grid[1][1] and grid[0][2] to water and get 2 disconnected island.
</pre>

<p><strong class="example">Example 2:</strong></p>
<img alt="" src="https://assets.leetcode.com/uploads/2021/12/24/land2.jpg" style="width: 404px; height: 85px;" />
<pre>
<strong>Input:</strong> grid = [[1,1]]
<strong>Output:</strong> 2
<strong>Explanation:</strong> Grid of full water is also disconnected ([[1,1]] -&gt; [[0,0]]), 0 islands.
</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;= 30</code></li>
	<li><code>grid[i][j]</code> is either <code>0</code> or <code>1</code>.</li>
</ul>

 class Solution {
public:
    void bfs(vector<vector<int>>&visited,int i,int j){
        int n=visited.size();
        int m=visited[0].size();
        vector<int>drow={0,1,0,-1};
        vector<int>dcol={-1,0,1,0};
        queue<pair<int,int>>q;
        q.push({i,j});
        visited[i][j]=1;
        while(!q.empty()){

            int row=q.front().first;
            int col=q.front().second;
            q.pop();
            for(int i=0;i<4;i++){
                int nrow=row+drow[i];
                int ncol=col+dcol[i];
                if(nrow<n&&nrow>=0&&ncol<m&&ncol>=0){
                    if(visited[nrow][ncol]==-1){
                        q.push({nrow,ncol});
                        visited[nrow][ncol]=1;
                    }
                }
            }
        }
    }
    int no_of_connected_components(vector<vector<int>>grid){
        int n=grid.size();
        int m=grid[0].size();
        int count=0;
        vector<vector<int>>visited(n,vector<int>(m,-1));
        for(int i=0;i<n;i++){
            for(int j=0;j<m;j++){
                if(grid[i][j]==0){
                    visited[i][j]=0;
                }
            }
        }
        for(int i=0;i<n;i++){
            for(int j=0;j<m;j++){
                if(visited[i][j]==-1){
                    bfs(visited,i,j);
                    count++;
                }
            }
        }
        return count;
    }
    int get_days(vector<vector<int>>grid,int days){
        int n=no_of_connected_components(grid);
        if(n==1){
            for(int i=0;i<grid.size();i++){
                for(int j=0;j<grid[0].size();j++){
                    if(grid[i][j]==1){
                        grid[i][j]=0;
                        if(no_of_connected_components(grid)!=1)return 1;
                        grid[i][j] = 1;
                    }
                }
            }
            return 2;
        }
        else return 0;
    }
    int minDays(vector<vector<int>>& grid) {
        return get_days(grid,0);
    }
};
55820