<p>You are given an <code>m x n</code> binary matrix <code>grid</code>. An island is a group of <code>1</code>&#39;s (representing land) connected <strong>4-directionally</strong> (horizontal or vertical.) You may assume all four edges of the grid are surrounded by water.</p>

<p>The <strong>area</strong> of an island is the number of cells with a value <code>1</code> in the island.</p>

<p>Return <em>the maximum <strong>area</strong> of an island in </em><code>grid</code>. If there is no island, return <code>0</code>.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>
<img alt="" src="https://assets.leetcode.com/uploads/2021/05/01/maxarea1-grid.jpg" style="width: 500px; height: 310px;" />
<pre>
<strong>Input:</strong> grid = [[0,0,1,0,0,0,0,1,0,0,0,0,0],[0,0,0,0,0,0,0,1,1,1,0,0,0],[0,1,1,0,1,0,0,0,0,0,0,0,0],[0,1,0,0,1,1,0,0,1,0,1,0,0],[0,1,0,0,1,1,0,0,1,1,1,0,0],[0,0,0,0,0,0,0,0,0,0,1,0,0],[0,0,0,0,0,0,0,1,1,1,0,0,0],[0,0,0,0,0,0,0,1,1,0,0,0,0]]
<strong>Output:</strong> 6
<strong>Explanation:</strong> The answer is not 11, because the island must be connected 4-directionally.
</pre>

<p><strong class="example">Example 2:</strong></p>

<pre>
<strong>Input:</strong> grid = [[0,0,0,0,0,0,0,0]]
<strong>Output:</strong> 0
</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;= 50</code></li>
	<li><code>grid[i][j]</code> is either <code>0</code> or <code>1</code>.</li>
</ul>

class Solution {
public:
   int m;
   int n;
   vector<vector<int>>directions = {{0,-1},{0,1},{-1,0},{1,0}};

   int dfs(vector<vector<int>>& grid,int i,int j,unordered_set<string>&visited ){
             if(i<0 || i>=m || j<0 || j>=n || grid[i][j]==0 || visited.count(to_string(i)+","+to_string(j))){
                   return 0;
             }

             visited.insert(to_string(i)+","+to_string(j));


             int area = 1;

            for(auto &dir : directions){
                int new_i = i+dir[0];
                int new_j = j+dir[1];
                area += dfs(grid,new_i,new_j,visited);
            }
      return area;
             
   }

    int maxAreaOfIsland(vector<vector<int>>& grid) {
          
           m = grid.size();
           n = grid[0].size();

           unordered_set<string>visited;
           int area = 0;


          for(int i =0;i<m;i++){
            for(int j = 0;j<n;j++){

              if(grid[i][j]==1 && visited.count(to_string(i)+","+to_string(j))==0 ){
                 area = max(area,dfs(grid,i,j,visited));
              }
            }
          }
          return area;
    }
};
35350