<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 dfs(int row,int col,vector<vector<int>>&grid,int n,int m,vector<vector<bool>>&vis){
        if(row>=n||col>=m||row<0||col<0||vis[row][col]||grid[row][col]==0) return;

        vis[row][col]=true;

        dfs(row+1,col,grid,n,m,vis);
        dfs(row-1,col,grid,n,m,vis);
        dfs(row,col+1,grid,n,m,vis);
        dfs(row,col-1,grid,n,m,vis);
    }
    int countislands(vector<vector<int>>grid,int n,int m){
        int island=0;
        
        vector<vector<bool>>vis(n,vector<bool>(m,false));
        for(int i=0;i<n;i++){
            for(int j=0;j<m;j++){
                if(grid[i][j]==1&&!vis[i][j]){
                    dfs(i,j,grid,n,m,vis);
                    island++;
                }
            }
        }
        return island;
    }
    int minDays(vector<vector<int>>& grid) {
        int n=grid.size();
        int m=grid[0].size();

        int island=countislands(grid,n,m);
        if(island!=1) return 0;
       // int count=0;
        for(int i=0;i<n;i++){
            for(int j=0;j<m;j++){
                if(grid[i][j]==1){
                    grid[i][j]=0;
                   int count=countislands(grid,n,m);
                   if(count==0||count>1) return 1;
                   grid[i][j]=1;
                }
            }
        }

        return 2;
    }
};
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