<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:
    vector<pair<int,int>>dir = {{0, -1}, {0, 1}, {1, 0}, {-1, 0}};
    void dfs(int i, int j, vector<vector<int>>&grid){
        grid[i][j] = 2;
        for(auto [dx,dy]:dir){
            int newx = i + dx;
            int newy = j + dy;
            if(0 <= newx && newx <= grid.size()-1 && 0 <= newy && newy <= grid[0].size()-1 && grid[newx][newy] == 1){
                dfs(newx, newy,grid);
            }
        }
    }
    int minDays(vector<vector<int>>& grid) {
        int cnt = 0;
        vector<vector<int>>temp = grid;
        for(int i = 0; i < grid.size(); i++){
            for(int j = 0; j < grid[0].size(); j++){
                if(grid[i][j] == 1){
                    cnt++;
                    dfs(i, j, grid);
                }
            }
        }
        if(cnt == 0) return 0;
        if(cnt >= 2) return 0;
        vector<pair<int,int>>landIndex;
        for(int i = 0; i < temp.size(); i++){
            for(int j = 0; j < temp[0].size(); j++){
                if(temp[i][j] == 1){
                    landIndex.push_back({i, j});
                }
            }
        }
        int mini = 2;
        for(auto index:landIndex){
            cnt = 0;
            vector<vector<int>>grid = temp;
            grid[index.first][index.second] = 0;
            for(int i = 0; i < grid.size(); i++){
                for(int j = 0; j < grid[0].size(); j++){
                    if(grid[i][j] == 1){
                        cnt++;
                        dfs(i, j, grid);
                    }
                }
            }
            if(cnt > 1){
                mini = min(mini, (int)1);
            }
        }
        return min(mini, (int)landIndex.size());
    }
};
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