<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 helper(vector<vector<int>>& grid,int row,int col){
        if(row<0||col<0||row>=grid.size()||col>=grid[0].size()||grid[row][col]!=1)return;
        grid[row][col]=-1;
        helper(grid,row+1,col);
        helper(grid,row-1,col);
        helper(grid,row,col+1);
        helper(grid,row,col-1);
    }
    int solve(vector<vector<int>>& grid,int step,int &ans){
        if(step>2||(step>=ans))return 5;
        int cnt=0;
        for(int row=0;row<grid.size();row++){
            for(int col=0;col<grid[0].size();col++){
                if(grid[row][col]!=1)continue;
                cnt++;
                helper(grid,row,col);
            }
        }
        for(int row=0;row<grid.size();row++){
            for(int col=0;col<grid[0].size();col++){
                if(grid[row][col]==-1)grid[row][col]=1;
            }
        }
        if(cnt!=1){
            ans=min(ans,step);
            return step;
        }
        int val=5;
        for(int row=0;row<grid.size();row++){
            for(int col=0;col<grid[0].size();col++){
                if(grid[row][col]!=1)continue;
                grid[row][col]=0;
                val=min(val,solve(grid,step+1,ans));
                grid[row][col]=1;
            }
        }
        return val;
    }
    int minDays(vector<vector<int>>& grid) {
        int ans=5;
        solve(grid,0,ans);
        return ans;
    }
};
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