<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<vector<int>>vis;
    vector<pair<int,int>>moves = {{1,0},{-1,0},{0,1},{0,-1}};
    int n,m;
    void bfs(int x, int y, vector<vector<int>>&grid){
        queue<pair<int,int>>q;
        q.push({x,y});
        vis[x][y] = 1;
        while(!q.empty()){
            auto node = q.front();
            q.pop();
            for(auto i : moves){
                int nx = node.first + i.first;
                int ny = node.second + i.second;
                if(nx>=0 && nx<n && ny>=0 && ny<m && vis[nx][ny] == 0 && grid[nx][ny] == 1){
                    vis[nx][ny] = 1;
                    q.push({nx,ny});
                }
            }
        }
    }

    int findConnectedComp(vector<vector<int>>&grid){
        n = grid.size(), m = grid[0].size();
        vis.assign(n, vector<int>(m, 0));
        int comp = 0;
        for(int i=0;i<n;i++){
            for(int j=0;j<m;j++){
                if(!vis[i][j] && grid[i][j] == 1){
                    comp++;
                    bfs(i,j,grid);
                }
            }
        }
        return comp;
    }

    int minDays(vector<vector<int>>& grid) {
        n = grid.size(), m = grid[0].size();
        int comp = findConnectedComp(grid), ans = 2;
        if(comp != 1){
            return 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 connComp = findConnectedComp(grid);
                    if(connComp != 1){
                        return 1;
                    }
                    grid[i][j] = 1;
                }
            }
        }
        
        return ans;
    }
};
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