<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 {
    vector<int> a{1, -1, 0, 0}, b{0, 0, 1, -1};
public:
    void helper(vector<vector<int>>& grid, vector<vector<bool>>& vis, int i, int j) {
        int row = grid.size();
        int col = grid[0].size();
        queue<pair<int, int>> q;
        q.push({i, j});
        vis[i][j] = true;
        
        while (!q.empty()) {
            auto front = q.front();
            q.pop();
            int r = front.first;
            int c = front.second;
            
            for (int k = 0; k < 4; k++) {
                int newX = a[k] + r;
                int newY = b[k] + c;
                if (newX >= 0 && newY >= 0 && newX < row && newY < col && grid[newX][newY] == 1 && !vis[newX][newY]) {
                    q.push({newX, newY});
                    vis[newX][newY] = true;
                }
            }
        }
    }

    int minDays(vector<vector<int>>& grid) {
        int row = grid.size();
        int col = grid[0].size();
        vector<vector<bool>> vis(row, vector<bool>(col, false));
        int count = 0;
        vector<pair<int, int>> v;
        for (int i = 0; i < row; i++) {
            for (int j = 0; j < col; j++) {
                if (grid[i][j] == 1) {
                    v.push_back({i, j});
                    if (!vis[i][j]) {
                        helper(grid, vis, i, j);
                        count++;
                    }
                }
            }
        }

        if (count != 1) {
            return 0;
        }
        if(v.size() == 1)
            return 1;
        for (auto arr : v) {
            grid[arr.first][arr.second] = 0;
            vector<vector<bool>> vi(row, vector<bool>(col, false));
            count = 0;

            for (int i = 0; i < row; i++) {
                for (int j = 0; j < col; j++) {
                    if (grid[i][j] == 1 && !vi[i][j]) {
                        helper(grid, vi, i, j);
                        count++;
                    }
                }
            }

            grid[arr.first][arr.second] = 1;
            if (count > 1) {
                return 1; 
            }
        }

        return 2; 
    }
};

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