<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:
    int cnt = 0;
    void solve(vector<vector<int>>& grid, int i, int j) {
        int n = grid.size(), m = grid[0].size();
        if (i < 0 || i >= n || j < 0 || j >= m || grid[i][j] != 1)
            return;

        grid[i][j] = 2;
        solve(grid, i + 1, j);
        solve(grid, i - 1, j);
        solve(grid, i, j + 1);
        solve(grid, i, j - 1);
    }

    int numberofisland(vector<vector<int>> grid) {
        int n = grid.size(), m = grid[0].size();
        cnt = 0;
        for (int i = 0; i < n; i++) 
            for (int j = 0; j < m; j++) 
                if (grid[i][j] == 1) {
                    solve(grid, i, j);
                    cnt++;
                }

        for (int i = 0; i < n; i++) {
            for (int j = 0; j < m; j++) {
                if (grid[i][j] == 2) {
                    grid[i][j] = 1;
                }
            }
        }
        return cnt;
    }

public:
    int minDays(vector<vector<int>>& grid) {
        int n = grid.size(), m = grid[0].size();
        int number = numberofisland(grid);
        
        if (number > 1 || number == 0)
            return 0;
        else {
            for (int i = 0; i < n; i++) 
                for (int j = 0; j < m; j++) 
                    if (grid[i][j] == 1) {
                        grid[i][j] = 0;
                        number = numberofisland(grid);
                        if (number > 1 || number == 0)
                            return 1;

                        grid[i][j] = 1;
                    }
        }
        return 2;
    }
};
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