<p>You are given a <strong>0-indexed</strong> <code>m x n</code> binary matrix <code>land</code> where a <code>0</code> represents a hectare of forested land and a <code>1</code> represents a hectare of farmland.</p>

<p>To keep the land organized, there are designated rectangular areas of hectares that consist <strong>entirely</strong> of farmland. These rectangular areas are called <strong>groups</strong>. No two groups are adjacent, meaning farmland in one group is <strong>not</strong> four-directionally adjacent to another farmland in a different group.</p>

<p><code>land</code> can be represented by a coordinate system where the top left corner of <code>land</code> is <code>(0, 0)</code> and the bottom right corner of <code>land</code> is <code>(m-1, n-1)</code>. Find the coordinates of the top left and bottom right corner of each <strong>group</strong> of farmland. A <strong>group</strong> of farmland with a top left corner at <code>(r<sub>1</sub>, c<sub>1</sub>)</code> and a bottom right corner at <code>(r<sub>2</sub>, c<sub>2</sub>)</code> is represented by the 4-length array <code>[r<sub>1</sub>, c<sub>1</sub>, r<sub>2</sub>, c<sub>2</sub>].</code></p>

<p>Return <em>a 2D array containing the 4-length arrays described above for each <strong>group</strong> of farmland in </em><code>land</code><em>. If there are no groups of farmland, return an empty array. You may return the answer in <strong>any order</strong></em>.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>
<img alt="" src="https://assets.leetcode.com/uploads/2021/07/27/screenshot-2021-07-27-at-12-23-15-copy-of-diagram-drawio-diagrams-net.png" style="width: 300px; height: 300px;" />
<pre>
<strong>Input:</strong> land = [[1,0,0],[0,1,1],[0,1,1]]
<strong>Output:</strong> [[0,0,0,0],[1,1,2,2]]
<strong>Explanation:</strong>
The first group has a top left corner at land[0][0] and a bottom right corner at land[0][0].
The second group has a top left corner at land[1][1] and a bottom right corner at land[2][2].
</pre>

<p><strong class="example">Example 2:</strong></p>
<img alt="" src="https://assets.leetcode.com/uploads/2021/07/27/screenshot-2021-07-27-at-12-30-26-copy-of-diagram-drawio-diagrams-net.png" style="width: 200px; height: 200px;" />
<pre>
<strong>Input:</strong> land = [[1,1],[1,1]]
<strong>Output:</strong> [[0,0,1,1]]
<strong>Explanation:</strong>
The first group has a top left corner at land[0][0] and a bottom right corner at land[1][1].
</pre>

<p><strong class="example">Example 3:</strong></p>
<img alt="" src="https://assets.leetcode.com/uploads/2021/07/27/screenshot-2021-07-27-at-12-32-24-copy-of-diagram-drawio-diagrams-net.png" style="width: 100px; height: 100px;" />
<pre>
<strong>Input:</strong> land = [[0]]
<strong>Output:</strong> []
<strong>Explanation:</strong>
There are no groups of farmland.
</pre>

<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li><code>m == land.length</code></li>
	<li><code>n == land[i].length</code></li>
	<li><code>1 &lt;= m, n &lt;= 300</code></li>
	<li><code>land</code> consists of only <code>0</code>&#39;s and <code>1</code>&#39;s.</li>
	<li>Groups of farmland are <strong>rectangular</strong> in shape.</li>
</ul>

class Solution {
public:
    void solve(vector<vector<int>>& land,vector<int> &coord,vector<vector<int>> &vis,int i,int j)
    {
        vis[i][j]=1;

        int dx[4]={-1,0,1,0};
        int dy[4]={0,1,0,-1};
        if(i+1>=land.size() && j+1>=land[0].size())
        {
            coord.push_back(i);
            coord.push_back(j);
            return;
        }
        else if(i+1>=0 && i+1<land.size() && j+1>=0 && j+1<land[0].size() && land[i+1][j] ==0 && land[i][j+1]==0)
        {
            coord.push_back(i);
            coord.push_back(j);
            return;
        }
        else if(i+1>=land.size() && j+1<land[0].size() && land[i][j+1]==0)
        {
            coord.push_back(i);
            coord.push_back(j);
            return;
        }
        else if(j+1>=land[0].size() && i+1<land.size() && land[i+1][j]==0)
        {
            coord.push_back(i);
            coord.push_back(j);
            return;
        }
        for(int k=0;k<4;k++)
        {
            int nx=i+dx[k];
            int ny=j+dy[k];
            if(nx>=0 && nx<land.size() && ny>=0 && ny<land[0].size() && !vis[nx][ny] && land[nx][ny]==1)
            {
                solve(land,coord,vis,nx,ny);
            }
        }
        
    }
    vector<vector<int>> findFarmland(vector<vector<int>>& land) {
        vector<vector<int>> ans;
        
        int rows=land.size();
        int cols=land[0].size();
        vector<vector<int>> vis(rows,vector<int>(cols,0));
        for(int i=0;i<rows;i++)
        {
            for(int j=0;j<cols;j++)
            {
                vector<int> coord;
                if(!vis[i][j] && land[i][j]==1)
                {
                    coord.push_back(i);
                    coord.push_back(j);
                    solve(land,coord,vis,i,j);
                }
                if(!coord.empty())
                {
                    ans.push_back(coord);
                }
            }
        }
        return ans;
    }
};
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